Tank turnover theories

Jordanlp

I’ve noticed when reading articles and care sheets about different types of fish, and also on Internet forums people often mention minimum times you should turn over the tank volume, often ridiculously high ratios like 10 times the tank volume are quoted, to me it seems without any workings or science to back this up.

While I agree with the general consensus that more filtration is never a bad thing (unless you have fish that struggle to swim in a lot of movement) but I’m interested as to why a certain flow rate would be needed in an aquarium? If your filter has enough media to handle the bio load, and you have sufficient aeration/movement, I struggle to see why anyone would strive to achieve 300 gallons of flow an hour in say a 30 gallon tank, or even 5 times the volume. Seems a bit like the inch per gallon rule to me, something people quote without really knowing too much about it. I can see why in heavily planted tanks it’s more important, but African cichlid keepers seem to think it’s very important and they don’t have plants.

I’d like to know people’s thoughts and theories on this, as it’s something I completely overlook, after all my mechanical filtration, bio media and pipes, my canister filter only has an actual output of about 40% of the manufactures quoted flow, which is about 2.5 times the tank volume, but as far as I can tell it still easily handles (no ammonia or nitrite) the bio load in quite heavily stocked tank.
 

BigManAquatics

Some people it is just personal preference for such high flow rates. Sometimes i feel it is also a person justifying to themselves why the dropped several hundred $$ on a filter. In a lot of cases, the main reason people mess with that stuff, though they won't admit it, is because they are really searching for "how to not have to do water changes".

There probably are some fish put there who like such a high flow rate. Most of mine certainly don't.
 
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Jordanlp

Some people it is just personal preference for such high flow rates. Sometimes i feel it is also a person justifying to themselves why the dropped several hundred $$ on a filter. In a lot of cases, the main reason people mess with that stuff, though they won't admit it, is because they are really searching for "how to not have to do water changes".

There probably are some fish put there who like such a high flow rate. Most of mine certainly don't.

Seems that way to me especially about people justifying spending a lot of money, it must be a filter manufactures dream. In my 33 gallon tank I always assumed I ‘over filtered’ using a canister filter that manufacturer states has a flow rate of 200 GPH and rated for a tank up to 80 gallons, but when I’ve measured the flow I’m only actually turning the tank over around 2.5 times an hour, if I wanted to achieve the turnover that many people reccomend I reckon I’d have to buy a 250 gallon filter or numerous smaller filters for a 33 gallon tank, seems a bit crazy to me.
 
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Basil

While having a ton of filtration probably doesn’t hurt, having too much flow probably does stress some fish.
When I set up my 75 g, I went with the recommendation from my good LFS of a Fluval 406 for it. Haven’t had any issues. I have a Fluval 307 on my one 40 breeder.
For those who have several filters in their tanks, I’m always curious how they are set up. I had enough trouble with the placement of intake and output tubes of one canister filter lol!
 
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pagoda

In my case its the aquariums that suit my room space always seem to come with all the gubbins (filter, heater etc). That is absolutely fine but over the years I have found that the filters provided with the aquarium are often at the bare minimum and require far more regular maintenance - insert changes etc.

Whereas replacing those "came in the box" filters with something more advanced and frequently that comes with a stronger flow does tend to lead to healthier fish in the longterm. That doesn't mean you can escape your weekly maintenance though such as water changes, you should always follow your weekly routine in that respect regardless of filter as that is part of the general animal husbandry to keep everything just so.

Another reason why I upgrade the filters, and buy the same ones for each aquarium is that when it comes to spares and replacing media, I can stockpile a bit thus stay prepared for any issues that might arise. Currently I have 4 aquariums, 2 x Aquael hex and 2 x Ciano Aqua and all have exact same external filter, Tetra EX600 Plus, the 5th aquarium, another Aquael hex will also have the same setup on filtering too once everything arrives in a couple weeks time.

I guess there will always be those who go up on filtration to escape the weekly maintenance but I would hope that they are a minority of fishkeepers.
 
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Jordanlp

In my case its the aquariums that suit my room space always seem to come with all the gubbins (filter, heater etc). That is absolutely fine but over the years I have found that the filters provided with the aquarium are often at the bare minimum and require far more regular maintenance - insert changes etc.

Whereas replacing those "came in the box" filters with something more advanced and frequently that comes with a stronger flow does tend to lead to healthier fish in the longterm. That doesn't mean you can escape your weekly maintenance though such as water changes, you should always follow your weekly routine in that respect regardless of filter as that is part of the general animal husbandry to keep everything just so.

Another reason why I upgrade the filters, and buy the same ones for each aquarium is that when it comes to spares and replacing media, I can stockpile a bit thus stay prepared for any issues that might arise. Currently I have 4 aquariums, 2 x Aquael hex and 2 x Ciano Aqua and all have exact same external filter, Tetra EX600 Plus, the 5th aquarium, another Aquael hex will also have the same setup on filtering too once everything arrives in a couple weeks time.

I guess there will always be those who go up on filtration to escape the weekly maintenance but I would hope that they are a minority of fishkeepers.

You are 100% correct about the filters supplied with aquariums not being up to scratch, but that’s because they don’t have the filtration capacity more then flow IMO.

What I’m wanting to find more information about is the theory that you have to turn over the tank volume a certain number of times that is often quoted online and in articles. For me you either have enough media to grow enough bacteria to deal with waste or you don’t, the flow rate would have very little impact on that, the only time it would come into play is if certain fish prefer a higher flow or not, or like I say if you want to avoid deadspots in a heavily planted tank.
 
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Redviper

While having a ton of filtration probably doesn’t hurt, having too much flow probably does stress some fish.

There are 4 ways I know of to reduce the impact of a filters return flow, if needed. Those being spin pipes, angling your filter return directly at a tank wall/angling it toward the surface and spray bars. Having fish with different body types, I noticed that they've learned to enjoy dedicated, tunable flow, and have been physically enhanced by it. As another poster put it: "Exercise and oxygen."

OT: The OP's concerns are, and have been long-standing mysteries for me as well. With engineers on staff, why not design filters\mats that produce proper flow rates that fish truly and verifiably need to prosper? I can only speak for myself in this, but I'd gladly pay a premium for a filter that did it's job right. A tip: Based on the filter mats you use, its possible to reduce the drag on a filters throughput by a noticeable degree, without reducing filter efficacy.
 
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Islandvic

I think high turn over rates helps more with mechanical filtration by kicking up uneaten fish food and fish waste off the substrate and allowing the filter intakes to suck it in.

Otherwise, most times it's not needed.

Most breeders and fishkeepers with multiple tanks primarily rely on sponge filters for all their tanks' filtration needs.

For example, take a look at the YouTube channel Prime Time Aquatics. When the host Jason does a fish room tour of his basement, usually once or twice a year, most tanks have sponge filters, even the larger tanks. He will sometimes supplement with a Penguin 350 HOB, but most of his filtration is handled by sponge filters.

Also take look at the Andy Woods Cichlids channel on YT. He has 75g-125g tanks with massive SA and CA cichlids that mostly run sponge filters.

Point being, high turnover rates are not needed in most cases.
 
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Redviper

I think high turn over rates helps more with mechanical filtration by kicking up uneaten fish food and fish waste off the substrate and allowing the filter intakes to suck it in.

Except using YT videos as examples of the efficacy of sponge filters in general use doesn't quite compute for me. The tanks used in those vids mostly have a temporary look and feel to them that average home tanks don't. I'd very much like to know many people who run their community/adapted use tanks on sponge filters alone over the long haul. Corey at ACO, another YT channel, talked in detail about SF's while demonstrating his topic on a huge tank behind him.

This tank was unusually large, fresh and populated to a degree, but was otherwise bare. In fact he showed the same tank in his next vid, about achieving water clarity I think. It wasn't populated this time but had a substrate layer.
 
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Flyfisha

You did try Islandvic?
If people don’t want to see 14 inch fish living for ten plus years on only sponge filters we can’t make people look?

As to turnover per hour?
I don’t understand where half these numbers come from. Goldfish as an example are often supposed to have some of the most ridiculous turnover rates. I don’t keep goldfish but I see a few in some places with very little turnover.
 
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Redviper

Since I'm not always good at understanding sarcasm, I'll take your post as just that, FlyFisha.

Islandvic, one thing I didn't mention in my response to: I've come to see the biofilm on the walls of my tank and on everything in it as beneficial, I've started to pay attention to its well being. That attention translates into dedicated flow. So far we've seen positive results. I say WE because my wife was the one who figured out how to program my flow pump. Credit where its due!
 
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Flyfisha

I don’t know if it’s sarcasm or not ? I am simply saying people in general don’t want to see things that contradict their already formed opinion. There are plenty of videos on the subject of wither or not a sponge filter is capable of filtering large tanks with large fish. Islandvic mentioned a good example of a long timer how has expensive wet pets he clearly cares about but chooses to filter with 1980s technology.

Just looking at this guy’s video it’s pretty clear to me the filters are not turning over 10 times the volume of tank water.


Warning video contains images of a fish pooping.
 
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JeremyW

I think that every hobby has a segment of the group whose enjoyment of the hobby is primarily rooted in the gear. They like researching, acquiring, setting up, and maintaining the equipment. They enjoy showing off their setup, and comparing it to other's. Sure they care about the fish and plants as well. But the real fun for them is in the gear.

These are the types of people who enjoy hot-rodding their cars. Do their vehicles really need a supercharger, or a spoiler, or a custom exhaust? The answer is absolutely not. But they enjoy it, so more power to them.

I think its the same in this hobby. You certainly don't need 300 GPH of filtration in a 30 gallon tank. But you don't need 800hp in a coupe either. People do it because they enjoy it.
 
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Redviper

I don’t know if it’s sarcasm or not?

Neither did I, and I said so.

I am simply saying people in general don’t want to see things that contradict their already formed opinion.

I'm sure you're right, but I'm not one of those people.

There are plenty of videos on the subject of wither or not a sponge filter is capable of filtering large tanks with large fish. Islandvic mentioned a good example of a long timer how has expensive wet pets he clearly cares about but chooses to filter with 1980s technology.

I've seen many of those videos. However since I've learned much of what I know of fish long before internet, I assimilate and weigh information on a slightly different mental "scale." In short, direct observation is my personal friend, as mush as possible that is.

Just looking at this guy’s video it’s pretty clear to me the filters are not turning over 10 times the volume of tank water.


Warning video contains images of a fish pooping.

That's not the point I thought you were trying to make. Sorry mate!
 
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Pfrozen

I do 10x in my 20g but I don't ever use floss or anything. Just course foam with ceramic beads in both HOB filters. Never had an issue with water clarity

Some fish prefer lower filtering, say 5x, while some need even higher, say 15x. These fish aren't kept in most tanks, so the "standard" is 10x for most commonly kept fish. If you up the difficulty to intermediate or expert you can expect to fiddle around with that number depending on what species you want

I agree that over filtering isn't necessary in most cases, but if you keep fish that don't mind a bit of flow then it doesn't hurt to be thorough
 
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RayClem

When a manufacturer rates an filter, the flow rates are measured with no filter media in the filter. If you add a foam prefilter and filter media, the flow rate will drop to a fraction of that level. As the filter media clogs with debris, the flow rate will drop even more. Thus, you might start with a filter rated at 500 gph thinking that is overkill for a 50 gallon tank (turnover rate of 10 x per hour), but once the filter is in use, the flow rate can slow to 100 gph or even less..

I have a 55 gallon tank that is filtered by an undergravel filter powered by two 300 gph powerheads, an Aquaclear 110 (500 gph) and an Aqueon 75 (400 gph). The HOB filters have foam prefilters that have to be cleaned every two weeks (one each week). Otherwise, the flow will drop off to a trickle. The tank is heavily stocked (platys are constantly giving birth). However, even though I have a rated turnover of 30 times the tank volume, the actual flow rate is such that even the 1/4" platy fry can swim around easily without fear of being sucked into the filters.

I have a 10 gallon aquarium that is lightly stocked and lightly planted. However, even in that aquarium I use a HOB filter rated for a 20 gallon aquarium (100 gph flow). The aquarium also contains an internal corner filter driven by an air pump. I believe all aquariums should have a minimum of two filters.

Do I have scientific evidence to support my conclusion that a minimum turnover rate of 10x the tank volume should be used based on manufacturers rated flow? No, I do not. However, I have been keeping fish for 60 years and my conclusion is based on my experience of keeping a variety of tanks ranging from a 2 1/2 gallon nano tank for a single betta up to 125 gallons saltwater tanks using a sump. Never purchase a filter based on the maximum size recommended by the manufacturer. If the manufacturer says the filter is suitable for a 20-40 gallon tank, it is far more suited for a 20 gallon tank than it is for a 40 gal.

I consider a 10x turnover rate to be the minimum acceptable for a tank, certainly not the "ridiculously high turnover rate" mentioned by the OP.

There are lots of reasons why larger filters are better. A larger filter costs only marginally more than a smaller filter. For example, an Aquaclear 70 rated for 300 gph can be purchased for $50. I consider it to be ideally suited for a 29 gallon tank with a 40 gallon tank being the largest. For a 29 gallon tank, you might be tempted to go with an Aquaclear 30 rated at 150 gph. However, that will cost you $33. Thus, for 66% of the price you get a filter that has half the flow rate and a filter box that only holds 43% as much media. Thus, I see the AC 70 as a much better value long term. More filter media means more surface area for growth of beneficial bacteria and less frequent cleaning cycles.

Likewise, I see something like an Aquaclear 50 (200 gph rated flow) to be ideally suited for a 20 gallon tank. The AC 50 costs $38, only $5 more than the AC 30 and $12 more than the AC 20. However, the AC 20 is only rated for 100 gph and is better suited for a 10 gallon tank than a 20 gallon.

I am only using the Aquaclear as an example as I have used a variety of brands over the years. However, I have found Aquaclear to be one of the most reliable; one AC 110 filter served me well for 20 years before it died.

I can understand why folks want to save money on their initial equipment purchases, but aquarium equipment is a long term investment. Not every filter will last that 20 years but most should give several years of service.
Thus, saving a few dollars up front is not always the best investment. The largest cost of keeping an aquarium is typically the cost of the livestock. Spending a few dollars extra to keep them healthy and happy is money well spent.
 
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Redviper

I do 10x in my 20g but I don't ever use floss or anything. Just course foam with ceramic beads in both HOB filters. Never had an issue with water clarity

Based on what you say here I'm starting to think that high turnover is largely based on tank size AND mats used by the Common Joe. My 125g is served by 160GPH and 295GPH rated filters. They both use a combination of Brightwater Bio Ceramic and Biohome Ultimate. Both types are very low restriction compared to most other ceramic biomedia. Both filters use 45 PPI foam for prefiltration. I don't get close to 10x turnover, but these filters combined help to create the backbone that makes possible water parameters and fish health that are peaches, even without 10x TO.
 
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RayClem

Based on what you say here I'm starting to think that high turnover is largely based on tank size AND mats used by the Common Joe. My 125g is served by 160GPH and 295GPH rated filters. They both use a combination of Brightwater Bio Ceramic and Biohome Ultimate. Both types are very low restriction compared to most other ceramic biomedia. Both filters use 45 PPI foam for prefiltration. I don't get close to 10x turnover, but these filters combined help to create the backbone that makes possible water parameters and fish health that are peaches, even without 10x TO.

Yes, Biohome ulitmate does provide a very high surface area for growth of beneficial bacteria. It actually works best in a low flow environment to allow growth of anaerobic bacteria to help control nitrates. However, Biohome ultimate is quite expensive. I have a SunSun HW-3000 canister filter that cost me about $150. It is rated at 792 gph, but it has a variable speed pump that I am running at half speed for use in a 40 gallon tank.

I use a sponge prefilter on the intake tube which I clean weekly to minimize having to clean the canister itself. the canister has four media trays. I filled the 1st tray with various foam pads. I filled the 2nd tray with about $25 worth of Seachem Matrix (pumice stone). I filled the top two trays with 5 lb of Biohome Ultimate which cost me $99. Thus, the filter plus media cost me nearly $300 total. At full capacity, using that media, that could easily handle 125 gallon tank. However, for that same $300, I could purchase three Aquaclear 110 filters and also get the job done.

For folks using sponge pads and ceramic rings in a canister filter, I still recommend using a filter rated for a 10x turnover. It is only when using high surface area media like lava, pumice and Biohome Ultimate than you can get by with a lesser flow. Remember that the filter is responsilbe for several things in the tank: providing mechanical filtration of particulates, providing surface area for growth of beneficial bacteria that maintain the nitrogen cycle. In some cases, chemical filtration can be included using carbon, Purigen, PolyFilter, phosphate removal media, etc. Furthermore, the filter provides water circulation that is necessary to maintain a uniform temperature throughout the tank and to allow for proper exchange of gases at the surface of the tank.

As long as the filtration system is able to provide all of those things, the tank will be OK. However, I have never found that a single HOB filter rated by the manufacturer at 5x the tank volume and using the manufacturer's included media will accomplish what is needed unless the tank is understocked and underfed. Perhaps using a canister filter with good media sized at 5x the tank volume will accomplish that.

Most new fishkeepers stock their tanks based on the size of the fish when they purchase them, not realizing that many will grow to several times that size at which time the tank will be seriously overstocked. This is why I recommend and use oversized filters. They are a good investment.
 
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Redviper

Yes, Biohome ulitmate does provide a very high surface area for growth of beneficial bacteria. It actually works best in a low flow environment to allow growth of anaerobic bacteria to help control nitrates. It actually works best in a low flow environment to allow growth of anaerobic bacteria to help control nitrates.

I guess I'll have to be satisfied with "lower flow", but it's working fine in the environment I've given it. Nitrate removal, if it truly works with this media, requires time and the cleanest oncoming water (to avoid the media clogging prematurely) you can feed the media with.

However, Biohome ultimate is quite expensive.

Sure, but not extravagantly so, considering the fact that I likely won't need to buy more, unless I need to kit another filter.

I have a SunSun HW-3000 canister filter that cost me about $150. It is rated at 792 gph, but it has a variable speed pump that I am running at half speed for use in a 40 gallon tank.

Nice find RC, though I can't see myself popping for another SunSun.

I use a sponge prefilter on the intake tube which I clean weekly to minimize having to clean the canister itself. the canister has four media trays. I filled the 1st tray with various foam pads. I filled the 2nd tray with about $25 worth of Seachem Matrix (pumice stone). I filled the top two trays with 5 lb of Biohome Ultimate which cost me $99. Thus, the filter plus media cost me nearly $300 total.

Great bang-for-the-buck there, especially considering the performance you're getting. My 600 is stuffed with (in order of oncoming water) 45PPI prefilter-two trays of BrightWater H-series sponge-2 trays of Brightwater ceramic-2 trays of what I think is 30PPI block sponge then ending in a tiny tray of 30PPI foam. My FX4 has standard ring foam on the way in then 30-45PPI foam-folowed by a deep tray of Biohome ceramic.

At full capacity, using that media, that could easily handle 125 gallon tank. However, for that same $300, I could purchase three Aquaclear 110 filters and also get the job done.

I'm sure you're right. I spent perhaps a $1300 plus a bit more on filtration kit and my Maxspect XF350 flow pump. Same destination different paths. I like that.

For folks using sponge pads and ceramic rings in a canister filter, I still recommend using a filter rated for a 10x turnover. It is only when using high surface area media like lava, pumice and Biohome Ultimate than you can get by with a lesser flow. Remember that the filter is responsilbe for several things in the tank: providing mechanical filtration of particulates, providing surface area for growth of beneficial bacteria that maintain the nitrogen cycle. In some cases, chemical filtration can be included using carbon, Purigen, PolyFilter, phosphate removal media, etc. Furthermore, the filter provides water circulation that is necessary to maintain a uniform temperature throughout the tank and to allow for proper exchange of gases at the surface of the tank.

All factual, I'm sure.

However, I have never found that a single HOB filter rated by the manufacturer at 5x the tank volume and using the manufacturer's included media will accomplish what is needed unless the tank is understocked and underfed. Perhaps using a canister filter with good media sized at 5x the tank volume will accomplish that.

I haven't seen a HOB with specs like that either, but I'm sure a DIY-type could produce one, likely requiring a block of cash.

Most new fishkeepers stock their tanks based on the size of the fish when they purchase them, not realizing that many will grow to several times that size at which time the tank will be seriously overstocked. This is why I recommend and use oversized filters. They are a good investment.

I like the way you view things wet, RC. That's why I quote you so much.

I learned how beautiful and motivational rapid growth can be.


20141028_171421_resized.jpg

My Alice doubled+ in size in just over a year. I think I might have helped by hand-feeding her orange\apple slices and unshelled Brazil nuts. She also picked off the fish already present in the tank before she arrived, one-by-one, at night serial killer-style. All except the BR in this background. I looked at my pacu with the same affection I've felt for any of my dog's\cat's.
 
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RayClem

I have been in the aquarium hobby for 60 years and have kept both freshwater and saltwater reef aquariums.

Although I am retired now, I was trained as a chemical engineer, so chemistry, thermodynamics, filtration, pumps and piping, mixing, heat exchange, absorption, evaporation, and gas exchange were all part of my engineering training. I have found that training to be very useful in my fishkeeping. In many ways, an aquarium is like a chemical factory, even though some is biochemistry. Understanding the principles of the various parts of that factory has been quite helpful.

If my fishkeeping experience and engineering and chemistry training can be helpful to others, I am happy to share it. Likewise, I continue to learn from other on the forum as well. You are never too old to learn something new.
 
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wishuponafish

I run 1 medium sized sponge filter (size of a soda can) in most of my tanks, and even my 40 breeder heavily stocked with sailfin mollies (very high bioload) and my 20 long with an axolotl and lots of guppies (high bioload) maintain a rock-steady 0 ammonia and nitrite.
The tank turnover is almost negligible and I'm not using any fancy media with the surface area of a football field but I'd say it's serving its bare minimum purpose as a filter in terms of processing nitrogenous toxins. Whether you have a 500 gph canister or a sponge filter, you'll still need to perform the same water changes to remove nitrates.

As for mechanical filtration and chemical filtration, I don't think they necessarily need to be included in the "bare minimum." It's convenient to clean and more visually appealing for the human to have poop and debris caught in the filter, but to the fish it's all the same. Whether the poop is on the floor or in the filter, it's still leaching ammonia and nasties into the water they're swimming in until the human comes in to take it out or detritivores break it down.
 
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RayClem

According to some scientific tests measuring the removal rate of ammonia added to aquariums, sponge filters are one of the more effective filter media at ammonia removal. If you are interested in the test method and results, you can search for the studies online. I have sponge filters all but one of my tanks, although I still like to maintain a plenty of water circulation using other filters as well.

If I were to use only a single sponge filter, I would want to use some type of powerhead to enhance the water movement. The large bubbles normally escaping from a sponge filter are not the best for generating circulation in the tank. An air stone does a better job. You need water movement for proper exchange of gases at the water surface. Excess carbon dioxide escapes and oxygen is dissolved into the water. If you are using only a sponge filter (no other pumps, filters, or air stones), if your were to purchase a dissolved oxygen meter, I suspect you would find the DO is less than optimal.
 
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Redviper

I have been in the aquarium hobby for 60 years and have kept both freshwater and saltwater reef aquariums.

Please tell me you aren't trying to establish your right to be the ultimate authority. I ask because your stating your creds the way you did could be interpreted as such.

edit: I'll be glad to respond to your post above once I can ascertain what sort of person I'm "chatting" with.

As an example of what's causing me to look at you sideways:

"If you are using only a sponge filter (no other pumps, filters, or air stones), if your were to purchase a dissolved oxygen meter, I suspect you would find the DO is less than optimal."

When/if, I come to the conclusion that I need such a device, I'll buy it based on my own observations and knowledge. BTW, I'm sure you noticed that I own and use one of the best surface agitators avaliable (I'm preparted to buy another based on wow-factor alone), and that it circulates water in dozens of ways and that in doing so it exposes ALL water in my tank to the surface as quickly as I want (causing rapid gas exchange), which means as fast a flow as my stock is comfortable with.

In closing (and to blow MY horn a tiny bit) you should know that offering advice unbidden is considered "rude" where I came from. That place was the west and near west sides of Chicago. I had a perfect record in honoring that unspoken rule, from both sides of the coin. As for filter mats, well, ! thought we had discussed that topic as equals a while back. NOW I know why you come off as a Vulcan admirer.
 
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RayClem

Redviper

No, I do not consider myself to be an ultimate authority; not by any means. I do believe I have knowledge that is worth sharing, so I share it.

I clearly stated " Likewise, I continue to learn from others on the forum as well. You are never too old to learn something new." There are a lot of folks on the forum that I consider to have worthwhile knowledge. I have always believed that to success in this world, you have to use all the brains God gave you and all you can borrow along with way. I gladly learn from others. Sometimes they correct my shortcomings and errors; I appreciate that. If I considered myself to be an "ultimate authority" I would be insulted by such corrections. I assure you that I do not feel that way.

If you will read my statement carefully, I stated: "If you are using only a sponge filter (no other pumps, filters, or air stones), if your were to purchase a dissolved oxygen meter, I suspect you would find the DO is less than optimal." I have absolutely no idea why you would think that statement was directed at you; I was not thinking about you in any way when I wrote it. I was thinking only of those who think a cheap sponge filter is the only thing they need.

The statement only applies to those who have a simple sponge filter as their only means of filtration and water circulation. It does not apply to anyone who is using powerheads, canister filters, HOB filters, or even an airstone. Since you are using canister filters and a Maxspect XF350 flow pump, you have more than enough circulation to achieve proper gas transfer.

I do not know why you think my comment about a dissolved oxygen meter was unsolicited advice to purchase one. I do not own one and would never consider doing so. I would never recommend that anyone else purchase one. My advice, unsolicited or otherwise, is to provide adequate water circulation by whatever means possible.

I am not quite sure what you mean by a Vulcan Admirer, unless you are referring to Spock of Star Trek fame. If you are inferring that I analyze things in the same way as Spock would have done, I take that as a compliment.

BTW- I have lived in the Chicago area for over 20 years. Thus, I am aware of some of the challenges of living on the west side of Chicago.
 
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IronPlanter

This is quite the interesting conversation.

In regard to turnover volume or flow rate through a filter I have never attempted to measure it, but now I'm also wondering what is adequate. I've tried a wide variety of filters. I've found running the size filter or combination of filters recommended for the total volume of water present with an adequately rated air pump is usually satisfactory; while not doing anything special or in excess of how the filter is designed to be used. While this may work it doesn't answer the question of adequate flow rate through a filter.

There are a few factors I think we have to consider.
  • How much waste is being produced?
  • How much waste needs to be broken down to maintain tank health?
  • What is the available surface area per volume of the filtration media (area where water flows over the surface of the media)?
  • How much waste can be broken down for a given volume of filter media?
With this in mind it would be possible to aproximate the amount of filter material needed for a given amount of bioload/waste/fish; as well as how many live plants may be needed, how much substrate might be beneficial and if one might want to leave some mulm in the tank or filter system.

The following articles can provide us with insight into the nitrification process, filter media, and flow rates. The more science heavy article sites a flow rate of 2% - 10% per day in commercial trickle filtration systems on fish farms. These systems typically have large volumes of water vs weight of fish in the system.

Heavy on the science article:
(PDF) Engineering analysis of the stoichiometry of photoautotrophic, autotrophic, and heterotrophic removal of ammonia-nitrogen in aquaculture systems
 
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Redviper

I clearly stated " Likewise, I continue to learn from others on the forum as well. You are never too old to learn something new."

Wow, just... wow! Conversation by adage isn't as rewarding as you obviously think it is. Like many others I had enough of that from my parents and won't have any more.

For goodness sake, you even claim to understand the trials of my former situation better than I do, when all I was intending to do was convey that I could be a lot rougher in my responses to your unsolicited and rapidly escalating lecture on how 2+2=4.

I could go on for a while more, but I've donated enough of my time trying to embody forum rules.
 
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RayClem

Few fishkeepers have the analytical equipment to measure such things a dissolved oxygen (DO) and biological oxygen demand (BOD). Yet they are important to the breakdown of biological waste. Few people know the specific surface area (area per unit volume) of the filter media they are using. Yet that is critical to the growth of bacteria that maintain the nitrogen cycle.

Thus, the best most of us can do is try not to over stock our aquariums or overfeed our fish to limit the BOD. We try to provide good water flow to maximize the dissolved oxygen concentration. Some HOB filters are poorly designed with respect to filter media, but customizing the filter media can make a huge difference to the performance of the filter.

If our filtrations systems were perfectly matched with the animal and plant stocking in our tanks, we would not need to do water changes. However, because our filters are not perfect and our stocking is not perfect, water changes are necessary. Those who change 50% of the water on a daily basis can probably manage without any filtration system at all. That is how bettas are maintained in small cups. There is no filter.

Those who do 50% water changes on a weekly basis need less filtration than someone who follows the Tetra recommendation of changing 30% of the water every 30 days. There are multiple ways of achieving the same end.

I always recommend extra filtration and good turnover rates because I know there are people who do not like to do large water changes. I maintain six tanks and the best I can manage is to change 15-20% of the water in each tank once a week. When I was working full time, water changes were done whenever I had time to do them, not necessarily on a routine schedule. I relied on filtration and water circulation to keep the water clean without my having to do frequent, large water changes.
 
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GlennO

I’d like to know people’s thoughts and theories on this, as it’s something I completely overlook, after all my mechanical filtration, bio media and pipes, my canister filter only has an actual output of about 40% of the manufactures quoted flow, which is about 2.5 times the tank volume, but as far as I can tell it still easily handles (no ammonia or nitrite) the bio load in quite heavily stocked tank.

That might be satisfactory and I don’t think it’s possible to generalise regarding flow rate except to say that a flow rate of 10x tank volume per hour (based on the manufacturer’s stated flow) would likely be satisfactory in nearly all circumstances so that’s probably where the commonly stated 8-10x turnover recommendation comes from. But the absolute minimum depends on your particular filter and tank setup. I remember a few decades ago when canisters were not as popular and Eheim and Fluval had much of the market. The Eheim 2217 was probably the most popular can and it was commonly purchased with 55 gal (around 200 litre) tanks. The 2217 is not a high flow filter though it contains loads of bio-media and being basket-less has virtually no bypass. The manufacturer states 1000LPH but plenty of real world tests come back at around 500LPH. So on a 55 gal that equates to an actual 2.5x turnover per hour. Thousands of hobbyists found it satisfactory and still do. I think it depends on the circumstances.
 
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Jordanlp

Do I have scientific evidence to support my conclusion that a minimum turnover rate of 10x the tank volume should be used based on manufacturers rated flow? No, I do not. However, I have been keeping fish for 60 years and my conclusion is based on my experience of keeping a variety of tanks ranging from a 2 1/2 gallon nano tank for a single betta up to 125 gallons saltwater tanks using a sump. Never purchase a filter based on the maximum size recommended by the manufacturer. If the manufacturer says the filter is suitable for a 20-40 gallon tank, it is far more suited for a 20 gallon tank than it is for a 40 gal.

I consider a 10x turnover rate to be the minimum acceptable for a tank, certainly not the "ridiculously high turnover rate" mentioned by the OP.

So when people advise 10 x the tank turnover, what they actually mean is use a filter that the manufacturer has rated to 10 x the tank turnover, not the actual output after media? That would make a lot more sense and seem a lot more realistic to be honest.

For example, I have a 33 gallon tank and use a Ehiem Ecco pro 300 (rated up to 80 gallons supposedly) filter with a supposed flow rate of 200 gallons per hour, if you go off that I would have 7 times the turnover per hour which is not a too far from 10. But after my mechanical filtration and biological media I actually get 40% of that, around 85 gallons per hour, which realistically only gives me 2.5 times turnover. Using that as an estimate, if I truly wanted 10 times the tank turnover I’d need a filter that advertised a flow rate of around 800 gallons per hour for a 33 gallon tank, which does seem unrealistic and major overkill. If as I’m now beginning to understand, people are talking about the manufactures best case scenario flow rate when they quote such figures, it makes a lot more sense and sizing a filter 10 times the advertised flow seems quite sensible.
 
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Redviper

The manufacturer states 1000LPH but plenty of real world tests come back at around 500LPH.

10x turnover seems like retail\aquarium physicist-style trickery. Most people who post their tank specs don't indicate that they've even approached such high turnover. For me and many others, it seems more about doing the best we can with limited resources, then judging success based on test numbers and the health/well-being/lack of morbidity in our stock. This approach works well for me, considering how adverse I am to to advanced mathmatics.

Also, believe it or not, there are forums where one can be argued into the dust for using advanced biomedia instead of stacks of dime-store dish cleaning pads, which just happens to be perfect for biological/adsobitive filtration. As if the only way to ride is to do so as cheaply as possible.

I'm ranting of course, but I feel strongly about my ability to come up with solutions based on observation and needs based reading/experimentation, without having "internet papers' of dubious value shoved at me under the table as a counter to what I say. Moreover, I respect the choices others make as well. After all I don't have to pay for anyone else's choices.
 
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GlennO

I think only the most dedicated and enthusiastic of hobbyists would achieve 10x actual turnover in their tanks. Good on them if they do. The 10x turnover is a handy reference when choosing a canister based on manufacturer ratings. It should ensure that you achieve 4-6x actual turnover. 4x is the usual generally recommended minimum hourly turnover for aquariums (if you place any value on general recommendations).
 
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Redviper

I think only the most dedicated and enthusiastic of hobbyists would achieve 10x actual turnover in their tanks. Good on them if they do. The 10x turnover is a handy reference when choosing a canister based on manufacturer ratings. It should ensure that you achieve 4-6x actual turnover. 4x is the usual generally recommended minimum hourly turnover for aquariums (if you place any value on general recommendations).

Well-reasoned, Glenn. It's always a good idea to include at least >some< reality in our musings.
 
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jtjgg

as a few people have already stated, once you put media into the filters, it lowers the actual flow rate significantly.

my Tidal 110's have the factory course foam, i add a layer of polyfil for fine mechanical, a bag of Matrix, a bag of Purigen, another bag of Matrix. I can see a lot of water coming through the overflow.

but on my sump, the flow is much less restricted. although the pump has to push the water up about 4' so that does lower the actual flow rate.
 
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Redviper

There are retail stand-alone pumps that produce truly awesome head pressure. Just the parallel mounted food grade pumps on my computer produce 39ft of head. I wish I had planned the room around my tank to support a sump, regardless of whether or not people say that they aren't "needed" with fresh.
 
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JeremyW

I think its important to remember that aquarium filtration is not just one function, but a combination of several. And any given filter is just one piece of equipment whose function can be replicated by other things. So I don't think its true to say that there is a specific filtration flow rate we need to achieve.

What I think is true is that there are certain processes necessary for a healthy aquarium. And our aquarium setups must create the conditions to support those processes in one way or another.

For example, we know that biological filtration is necessary and that much of it happens in the filter. But we also know that biological filtration happens in the substrate, and with plants. For certain setups biological filtration can happen entirely without a filter.

We know that surface agitation, and water circulation are necessary for oxygenation and gas exchange in general, and filters usually serve that purpose. But so do air stones, and powerheads. So once again, the function of filter can be replicated by other things.

Water clarity is perhaps the only thing that a filter is uniquely capable of fixing. But there are some issues with water clarity that a filter can not fix. And water clarity is not a great indicator of water quality from a fish's perspective.

And then there's all the variation we have in different tank sizes and shapes, different filter types, different stocking levels, different stocking combinations, different maintenance routines etc.

IMHO there really is no golden number for filtration flow rates. Because depending on what our setup is, we may need a big filter, a small filter, or no filter at all. As long as our setups are designed in such a way to meet the needs of a healthy contained ecosystem, then we're good.

With all that said, I totally understand the need to set a benchmark number as a guideline for new and casual hobbyists. A box rating of 10x your tank volume is as good a benchmark as any. But once you get your feet under you in this hobby, I think its unnecessary, and limiting, to cling to that benchmark as a hard and fast rule.

And for the record, I really like a good hang on back filter. Its a great piece of equipment that checks a lot of boxes for our aquarium needs all in a single tidy package. With a single power cord, and no additional parts or plumbing required, it takes care of water circulation, surface agitation, biological and mechanical filtration. No other piece of equipment in this hobby does so much with so little. They're highly accessible, customizable, available, and affordable. What's not to love?
 
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Redviper

Corey at aquarium Co-Op on the inherent complexity in configuring various types of filters.


Two aspects of fishkeeping I've tried to develop a deeper understanding of are feeding and the idea that all the available surfaces in my tank are refuge for BB.

I tend to overfeed any creature around me. My ma and dad being the same way, I can only assume a genetic component. In order to avoid this I've so far stopped using an auto feeder. Adopted a feeding schedule that offers food once in 24hrs and only enough that they can lap up in a couple of minutes. I've stopped snap feeding as well. Considering a weekly 40g swap, my average nitrate level is about 15ppm. I'd like to see 10ppm or less.

When I became aware of the fact that my entire tank could be viewed as a very large BB bed, the first thing that popped into my mind was "Emergency filter?". While there's no easy way to test the changes I've made so far regarding what happens in an emergency situation. There have, however been other positive changes due to my efforts to improve high-quality flow that I didn't expect and appreciate.

So I'm pleased with what I've learned and tried to implement. A less pleasant condition I heard about was the tendency of aquarists to fall into a change-for-the-sake-of-change cycle. I know exactly what this "condition" entails, which may be why I'm so protective/indulgent of my livestock.

IMO, Corey can be difficult to watch for long periods but this vid is worth it considering the nature of this thread.
 
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Redviper

This guy may have broached one of my filtration Holy Grails's. I won't sully things with editorializing, I'll just say "sustainable anaerobic filtration!" Goodnight, all!

Why Your Filter is TOO SMALL and NOT CYCLED
 
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Pfrozen

This guy may have broached one of my filtration Holy Grails's. I won't sully things with editorializing, I'll just say "sustainable anaerobic filtration!" Goodnight, all!

This guy is absolutely right for the most part. All of my tanks run at 0 nitrates and I make heavy use of ceramic beads. Just want to note that while yes, anaerobic bacteria are denitrifying bacteria by nature, it is common for aerobic bacteria to perform denitrification as well. Not really important at the end of the day but for someone who runs bare-bottom with 0 nitrates and well-oxygenated HOB filters it might make more sense to fully understand the diversity of these bacteria. I was just explaining this to another member

Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

This article explains how aerobic bacteria perform denitrification as well.

Also, during my research on blackwater tanks I found some interesting things too. Its well-accepted that microbe activity takes over a portion of the nitrogen cycle as pH drops, but many species of nitrosomonas and other common filter bacteria are able to continue the nitrogen cycle down to pH 3-4 without any problems as well. As pH drops, other species become more prominent to further compensate. It seems that these bacteria are diverse enough to handle a range of conditions
 
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RayClem

This guy may have broached one of my filtration Holy Grails's. I won't sully things with editorializing, I'll just say "sustainable anaerobic filtration!" Goodnight, all!


There is some truth in what PondGuru is saying. However, you have to realize that his video also serves as an infomercial for the BioHome filter media he helped develop and is trying to sell for monetary gain. As long as you realize his motives and are OK with them, that is fine.

I have used BioHome Ultimate in one of my filters since Christmas. It is effective; but it is expensive. I purchased it as an experiment. For someone who wants to run a small (low flow) filter in a large tank, it would be ideal. However, I have not used it long enough to say that is is a more cost effective alternative to lava rock and pumice stone (Seachem Matrix for example). I am pretty sure it is more effective than ceramic rings and bioballs on a volume basis; they are better in a large filter, However, due to the price differences, I do not know which represents the better value.

Simple sponge filters are the most cost effective filters, but they are not the most attractive.
 
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GlennO

I have no reason to disbelieve him, but still don't understand why he thinks that this "full cycle" is so important. What is the benefit of lowering nitrates to near zero unless you have an overstocked tank with consistently high nitrates despite regular water changes. Even if had near zero nitrates I would still feel it necessary to maintain my water changes in order to replenish minerals and prevent the build up of other potential toxins.
 
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