Fliter flow rate or capacity, which is more important?

[ikcdab]

I am looking to buy a new canister filter for a 300l aquarium. I have been looking at one that has a 12l water capacity and one that has an 9l capacity but a greater flow rate.

So which is better, a larger capacity so that I can get more media in, or a greater flow rate to turn the water over quicker?

The two filters are the aquis 1250 and the fluval 407.

Thanks

 

[Cherryshrimp420]

Fluval has been pretty reliable for me. Imo the canister that doesnt break or leak is the better one

 

[GlennO]

On a 300 litre tank I'd run both of them.

 

[Flyfisha]

I would also suggest running both if you can afford it? Or running the bigger one with a sponge filter one two in 300 litres/. 80 gallons.
That way one is ready to be cleaned and one was cleaned last month.

On the subject of what is more important flow or volume for media . The more I learn the less I know.

Lets say having spare volume when filter media gets dirty is never a bad thing. Just as having more flow than necessary is never bad when the flow slows down because it’s ready to be cleaned.

GlennO and anyone else following this thread . I visited one of the best breeders in my local club this morning. I am blown away by the little sponge filters the lack of tank size and low water level. A few snapshots of some of his breeding tanks that are all under 5 gallons. The sponge filters are in my ( old ) opinion totally inadequate the tanks are to small and the air running was not enough ( slow flow)

Sixteen adult killifish plus a few fry in this?

Note the size of the single tiny sponge filter in these tanks.More killifish in a half full K mart tank.

The tanks are all small guys.
Note the floating plants, sand wood and Anubis in this 3 ish gallon luxury accommodation.


To be fair this 30 gallon has lots of plants. Two snapshots from each end of the same tank. It’s not over stocked as a grow out , is it?

 

[jtjgg]

i prefer flow rate. the more times the water goes through the filter the better. a lot of the factory recommended tank volumes only give around 4x turnover rate.

you'll have to look at several factors such as stocking, understock = less waste to water volume ratio. overstocking will require higher turnover rate. plants or no plants, and how lightly or heavily planted? you can have less filtration with more plants as plants help convert a lot of the waste produced.

filter volume is almost negligible now with the high surface area bio media that is currently available such as Biomax (ceramic), Matrix (pumice), Biohomme (scintered glass), etc.

 

[GlennO]

Also the actual flow rates will be less than stated by the manufacturer. The specs for the Aqua One Aquis 1250 state a maximum flow rate of 1400 l/h. So very close to the Fluval 407 maximum flow rate of 1450 l/h. But the actual flow rate in practice for both filters would be closer to 900 l/h. Fluval actually states a circulation rate of 930 l/h. So each filter would turn over the tank volume approx. 3x per hour.

 

[diamonfingers]

This is very interesting as I talk to people on the internet I heard 2 opinions:

1) The more water turns in the filter the better, so a filter that will pass whole water aquarium 5x per hour is better than a filter that will pass 1x per hour

2) Slower turn rate is better, because passing the water quickly in the filter will not given enough time for the benefaction bacteria to do its job

so I will be interested to hear an answer too

If I was you, I would buy the biggest canister I can get fill it with all types of filter media. Better safe than sorry. SunSun makes cheaper canister filters but not too sure about the quality. I got EHEIM and so far so good. Great build quality and no noise. Very Effective.

I would also suggest running both if you can afford it? Or running the bigger one with a sponge filter one two in 300 litres/. 80 gallons.
That way one is ready to be cleaned and one was cleaned last month.

On the subject of what is more important flow or volume for media . The more I learn the less I know.

Lets say having spare volume when filter media gets dirty is never a bad thing. Just as having more flow than necessary is never bad when the flow slows down because it’s ready to be cleaned.

GlennO and anyone else following this thread . I visited one of the best breeders in my local club this morning. I am blown away by the little sponge filters the lack of tank size and low water level. A few snapshots of some of his breeding tanks that are all under 5 gallons. The sponge filters are in my ( old ) opinion totally inadequate the tanks are to small and the air running was not enough ( slow flow)
View attachment 857248
Sixteen adult killifish plus a few fry in this?
View attachment 857249
Note the size of the single tiny sponge filter in these tanks.View attachment 857250More killifish in a half full K mart tank.
View attachment 857251
The tanks are all small guys.View attachment 857252
Note the floating plants, sand wood and Anubis in this 3 ish gallon luxury accommodation.

View attachment 857253
View attachment 857255 To be fair this 30 gallon has lots of plants. Two snapshots from each end of the same tank. It’s not over stocked as a grow out , is it?

I talked to people online that say canister filter is overkill and for most non-gigantic tanks a sponge filter or a small HOB filter is more than adequate.

While it may be adequate to keep the fish alive (idk) my aquarium is a piece of furniture and I do not want to look at a yellow tank. I still do not know why fish tank water is yellow, they say tannins but even ones without wood has that color. I have chemipure in tank and I have the water quality I want! Those chemical filters are like magic!

 

[Flyfisha]

ikcdab I hope you realise the importance of your original question and why I am using this thread to explain my changing attitude? I hope you don’t mind?

I was in the beginning of my journey in the hobby of the opinion that water should pass through a filter as many times as possible. This may be true for removing solids? Picking up solids is not the most important thing a filter can do ( mechanical filtration ) I have always realised removing ammonia (biological filtration) is many times more important in keeping fish alive. Mechanical filtration is purely cosmetic especially if the filter remains full of solids for any amount of time as the poop is still in the water if it’s in a filter.
Note the healthy fish tank with 12 months worth of poop in the water on the filter in this video.

To this end I now believe even more so since my recent visit to a local club members fish room that slow flow is better than fast. Allowing the bacteria to be in contact with the ammonia for more time instead of passing the food ( ammonia) quickly past the bacteria.

diamonfingers
I also believe canister filters are overkill if we have the time to service smaller filters more than once a year. There is little doubt that hundreds of fish in a 40 gallon can be taken care of with a single hang on back filter as per the grow outs in this tank that had a single tidal HOB

 

[86 ssinit]

Many different beliefs on filtration. Many breeders use sponges. But they are breeding. Not many fish per tank so not much filtration needed. For a community tank like the ops 80g more filtration is needed. For me I would recommend 2 filters for ops tank. Neither would be a canister. To me they are the least useful filter. To many get them to never have to clean them and you end up with the filter pictured above. Not only is that filter filled with waste it’s flow rate is drastically reduced.

For your 80g I recommend the tidal 110 and an odyssea 250. Both great filters and probably the same price or cheaper than the fluval. The tidal will hold more than enough media and the odyssea is 2 sponges run through a powerhead. So you’ve got your sponge filter but turbocharged. Clean 1 every week while doing a 50% water change and you’ll have a clean healthy tank.

 

[RayClem]

Generally, the manufacturer of a filter will design it so that the capacity of the filter to contain filter media will be suitable for the flow rate of the filter. If the quantity of media is not sufficient for the flow rate, then small particles will pass through the filter and make the water cloudy.

I typically recommend a rated flow rate of 10X the tank capacity per hour. Thus, for a 300 liter tank (75 gallon) you will need a filter rated for 3000 liters per hour (750 gph), While this sounds like excessive water flow, by the time the filter is filled with media, the actual flow rate will be somewhere around half of this value.

Filter manufacturers often claim that their filter are good for tanks "up to" a certain tank size, but I have found that they are only effective for about half the maximum value. Thus, an Aquaclear 110 with a 500 gallon per hour flow rate works best on tanks no larger than 55 gallons (220 liters). Because canister filters can hold a larger quantity of media than HOB filters, you might get by with one rated less than 10X the tank capacity, but a single filter rated at 1400 lph might not be big enough.

I always recommend using at least two filters for any tank, especially one as large as 300 liters. An ideal setup would be the Fluval 407 canister rated at 930 liters per hour plus a Fluval/Aquaclear 110 HOB filter or Seachem Tidal 110 filter (2000 liter per hour). That combination will give you a rated flow of slightly under 3000 liters per hour. Once filled with media, the actual flow will be around 1400-1500 1500 liters per hour which is not excessive.

Just as important as the capacity and flow rate of the filters is the type of media you use in your filters. Some filter media like bioballs are not very effective in canister and HOB filters. They work great in shower/trickle filters in sump setups where large quantities of the bioballs can be used. Ceramic rings are somewhat better. The best media are made from porous volcanic rock such as pumice (Seachem Matrix is pumice that has been washed and graded), lava rock, and even perlite. There are synthetic media like Biohome ultimate that are designed to perform similar to lava rock. I have both Seachem Matric and Biohome Ultimate in my canister filter. While these rocks are good at biofiltration, they are not good at mechanical filtration. Using coarse, medium and fine sponge filters in your canister filter prior to the volcanic rock will help with both the mechanical and biological filtration.

 

[jtjgg]

not sure why some people believe the BB is unable to consume the ammonia/nitrite with higher flow rate filters vs slower flow rate filters. I mean, once your tank is cycled, whether the filter is 4x turnover rate or 8x turnover rate, there is 0 ammonia and 0 nitrite.

 

[ikcdab]

Thank you all for your replies that after very useful.

 

[ruud]

So which is better, a larger capacity so that I can get more media in, or a greater flow rate to turn the water over quicker?

The latter.

Cutting corners; "good bacteria" require dissolved oxygen, "bad bacteria" appear in low dissolved oxygen conditions. Because of this, canister filters can be less efficient than what you might expect and even become a source of trouble. I would choose higher flow in combination with only coarse filter media (or no media at all for planted tanks).

Studies on sewage treatment plants offer plenty of insight on this subject.

 

[RayClem]

The latter.

Cutting corners; "good bacteria" require dissolved oxygen, "bad bacteria" appear in low dissolved oxygen conditions. Because of this, canister filters can be less efficient than what you might expect and even become a source of trouble. I would choose higher flow in combination with only coarse filter media (or no media at all for planted tanks).

Studies on sewage treatment plants offer plenty of insight on this subject.

Exactly. The water flow has to be sufficient so that enough oxygen is carried through all of the filter media in the canister. If you have anerobic zones within the canister media, you want those zone to reside primarily within the deeper pores of the media. Otherwise, the anaerobic bacteria can produce hydrogen sulfide which is toxic. Having some anaerobic activity, however, is not a bad thing as anaerobic bacteria are responsible for denitrification, the conversion of nitrates into nitrogen gas.