75 Gallon Tank I've Done It, Perfect Cycle

TheeLadyG

Member
My tank:
75G freshwater
Black Diamond sand
Airstone strip
50G double sponge filter
Whisper 300 air pump
Cascade 1000 canister with custom media setup
2 fancy goldfish, about 1yr old
Set up since Dec 2018

I do water changes usually about every 10 days or so, and water test at the same time. I've been noticing that my nitrates have been steadily dropping... the last time I read above 10 was Feb 18. It has been my goal to have a "complete" cycle, as in, it processes nitrates into nitrogen gas.

My last 3 tests have shown 5 or less nitrates! I was skeptical so I tested my bowl of water plants and got 20... so my test is good?

I decided to test the limits of my system, so I went 21 days (!) without a water change. (Obviously I monitored my fish and tank for issues). I did my cleaning and water change today (wow what a mess, never going that long again). My tests all came out 0, I'm totally bragging but I HAD to share this with some people who would *get* how exciting this is.

I set up my canister filter "pondguru" style, that utilizes both aerobic and anaerobic bacteria for biological filtration. I also have allowed algae to grow as thick and lush as it darn well pleases on the back wall. Looks nice AND it's edible. (The only plant my fish hasn't destroyed haha). I think these two factors together have finally brought my nitrates to 0.

I've included a shot of my tank, it's still a little stirred up and bubbly from the water change.
Screenshot_20190426-140329_Gallery.jpg

20190426_144434.jpg
 

Skavatar

Member
awesome. looks great.

what media is in your canister?
 
  • Thread Starter

TheeLadyG

Member
Skavatar said:
awesome. looks great.

what media is in your canister?
3 trays.
Bottom: Coarse, Med and Fine sponges cut to fit
Middle: Marinepure CerMedia balls with Biohome minI filling between
Top: Same biomedia with a filter pad cuz I have them and why not

I rinsed my canister about a month and a half ago, and reconfigured it to this maybe 2 mos ago?

Here is the YouTube vid that put me on the path of styling my filter this way. It's long, but really worth it and has amazing clear info about the cycle and canister filters:
 

Skavatar

Member
nice, i've seen that video too. I heard good things about MarinePure and Biohome media.

I just bought a knock off Sun Sun 525gph 2 weeks ago. I have it set up almost the same. bottom tray is poly fill and one of the filter pads it came with. 2nd, tray is the ceramic beads from my old filter, plus some Pond Matrix. 3rd and 4th tray are all Pond Matrix. Just got the Pond Matrix delivered a few days ago. Hoping to get a complete cycle too.
 

oldsalt777

Member
TheeLadyG said:
My tank:
75G freshwater
Black Diamond sand
Airstone strip
50G double sponge filter
Whisper 300 air pump
Cascade 1000 canister with custom media setup
2 fancy goldfish, about 1yr old
Set up since Dec 2018

I do water changes usually about every 10 days or so, and water test at the same time. I've been noticing that my nitrates have been steadily dropping... the last time I read above 10 was Feb 18. It has been my goal to have a "complete" cycle, as in, it processes nitrates into nitrogen gas.

My last 3 tests have shown 5 or less nitrates! I was skeptical so I tested my bowl of water plants and got 20... so my test is good?

I decided to test the limits of my system, so I went 21 days (!) without a water change. (Obviously I monitored my fish and tank for issues). I did my cleaning and water change today (wow what a mess, never going that long again). My tests all came out 0, I'm totally bragging but I HAD to share this with some people who would *get* how exciting this is.

I set up my canister filter "pondguru" style, that utilizes both aerobic and anaerobic bacteria for biological filtration. I also have allowed algae to grow as thick and lush as it darn well pleases on the back wall. Looks nice AND it's edible. (The only plant my fish hasn't destroyed haha). I think these two factors together have finally brought my nitrates to 0.

I've included a shot of my tank, it's still a little stirred up and bubbly from the water change.
Screenshot_20190426-140329_Gallery.jpg

20190426_144434.jpg
Hello Thee...

Nicely done tank. I would recommend performing the large water change weekly. The reason is because water loses its ability to hold oxygen in a matter of a few days due to it constantly running through a filtering system. Minerals are also changed because of their exposure to oxygen and being used by the fish and plants. If you could test the oxygen and minerals in the water, you'd notice changes every day. The longer the same water stays in the tank the more it changes chemically. Make your water changes at least 50 percent weekly and you won't need to worry about ever testing the water chemistry. You'll know the water is "spot on" for the fish and plants, because you'll be replenishing oxygen and minerals before they are depleted.

Old
 
  • Thread Starter

TheeLadyG

Member
oldsalt777 said:
The reason is because water loses its ability to hold oxygen in a matter of a few days due to it constantly running through a filtering system. Minerals are also changed because of their exposure to oxygen and being used by the fish and plants.
I do have my water in constant motion with two bubbling sources and the canister filter flowing it through making sure it moves between the top and the bottom... how is it exactly that it loses the ability to hold oxygen? I can see the oxygen becoming depleted in a perfectly still water over time, but not water in motion. Because my water is warm I make extra sure to get good surface agitation and water movement (without making my fish uncomfortable!) I can say I did not notice any sort of behavioural change on my fish in the time that I went without any water change (trust me, I was watching carefully because I knew I was pushing my luck). No surface swimming, etc. The minerals thing I can get behind, that makes sense to me, but if water is being circulated and the surface tension properly broken it should keep the oxygen levels just fine?
 

oldsalt777

Member
TheeLadyG said:
I do have my water in constant motion with two bubbling sources and the canister filter flowing it through making sure it moves between the top and the bottom... how is it exactly that it loses the ability to hold oxygen? I can see the oxygen becoming depleted in a perfectly still water over time, but not water in motion. Because my water is warm I make extra sure to get good surface agitation and water movement (without making my fish uncomfortable!) I can say I did not notice any sort of behavioural change on my fish in the time that I went without any water change (trust me, I was watching carefully because I knew I was pushing my luck). No surface swimming, etc. The minerals thing I can get behind, that makes sense to me, but if water is being circulated and the surface tension properly broken it should keep the oxygen levels just fine?
Thee...

In the presence of nitrogen from the fish and plant waste material, oxygen is removed. If you feed plants commercial fertilizers, this is also a nitrogen source and more oxygen is removed from the tank water. The longer your tank goes between water changes, the more oxygen is removed. So, by simply removing the old, nitrogen filled water (pollution) and replacing that will pure, treated tap water you replenish oxygen. If you make the new water a bit cooler, more oxygen is added.

Old
 

McFly

Member
IF you do 50% weekly water changes, I agree, the water quality will
likely remain healthy, but I still recommend testing water none the less.
Trusting your municipal water source for 100% stability isn't a great idea.

I've always maintained that filtration, bioload and water volume dictate
how much and how often water should be changed. 50% weekly in my
60 gallon tank is a lot more work than necessary, and though I'm not
afraid of a little hard work, I do protest excessive hard work, and unnecessary
hard work.

My 60G tank does well with 25% weekly water changes. My nitrate stays below 40 ppm,
which is fine, considering my tap has 15 to 20ppm nitrate to begin with. How do
I know this? I performed 50% water changes, with the same test results as 25%
at the end of one week for a few weeks time.

I'm not discouraging anyone from doing 'what they do' to maintain a healthy
tank, I am saying that every tank is different... filtration, capacity, bioload, feeding,
planting, maintenance ALL contribute to water quality, and once you start getting
into larger tanks, a blanket "50% weekly" though may be more than adequate, it
may also be more work than required... which may also deter people from the hobby.
 

Skavatar

Member
TheeLadyG i've read previously that denitrification needs a source of carbon like alcohol or dried leaves or sugar. did you have anything like that in the tank?
 

IceForever

Member
I ordered some of that biohome ultimate after watching that video
 
  • Thread Starter

TheeLadyG

Member
Skavatar said:
TheeLadyG i've read previously that denitrification needs a source of carbon like alcohol or dried leaves or sugar. did you have anything like that in the tank?
I don't! It's possible that the biohome minI has its own. Maybe the black diamond sand? It is coal slag after all... but it's supposed to be as inert as glass?

I cleaned the algae off my fake plants last week and Sunny has been demolishing the wall of algae so I'm interested to see how I test tomorrow when I do my tank clean (inlaws coming this weekend so I'm making everything perfect)

oldsalt777 said:
Thee...

In the presence of nitrogen from the fish and plant waste material, oxygen is removed. If you feed plants commercial fertilizers, this is also a nitrogen source and more oxygen is removed from the tank water. The longer your tank goes between water changes, the more oxygen is removed. So, by simply removing the old, nitrogen filled water (pollution) and replacing that will pure, treated tap water you replenish oxygen. If you make the new water a bit cooler, more oxygen is added.

Old
Ok are you saying in the process of converting nitrogen to nitrogen gas that O2 is removed? The NO2 should offgas on its own through the water surface the same as O2 is drawn in by surface agitation. If my water is properly circulating it should have all the dissolved oxygen it needs, correct? My water is not stagnant, it is constantly replenishing its oxygen at the surface and circulating throughout my tank and filters. Am I mistaken?

Also, making the water cooler does not add O2, it makes chemical reactions happen slower so that the water holds on to more oxygen for longer. Fun fact: In arctic temps water can even become supersaturated with O2! It's essential for kickstarting life in a lot of places in the spring melt.
 

oldsalt777

Member
Hello Thee...

All good questions. I'm no chemist, but I understand the affect nitrogen has on oxygen. Inert gasses like nitrogen don't support breathing and reduce levels of oxygen whether it's in the air or in the water. So, you don't want dissolved nitrogen in the form of fish and plant waste material or fertilizers to build up the in the tank water, or you have oxygen deprivation, the fish have to work to breath and this causes stress. Stress we know in fish leads to heart and immune system problems. You want to constantly remove and replace most of the tank water weekly to remove nitrogen and replace oxygen.

I didn't say cooler water adds oxygen. Cooler water holds more oxygen than warm because there are more molecules in it. In cool water, molecules bunch together and don't escape very fast. This is why you want to keep the tank water on the cooler side to maintain a better oxygen level for the fish. Or, you add an air stone attached to an air pump to agitate the water and mix in more oxygen. Again, this is why you want to change a lot of water weekly. The action of the water splashing into the tank mixes oxygen into the water.

Hope this explanation helps.

Old
 
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TheeLadyG

Member
oldsalt777 said:
Hello Thee...

All good questions. I'm no chemist, but I understand the affect nitrogen has on oxygen. Inert gasses like nitrogen don't support breathing and reduce levels of oxygen whether it's in the air or in the water. So, you don't want dissolved nitrogen in the form of fish and plant waste material or fertilizers to build up the in the tank water, or you have oxygen deprivation, the fish have to work to breath and this causes stress. Stress we know in fish leads to heart and immune system problems. You want to constantly remove and replace most of the tank water weekly to remove nitrogen and replace oxygen.

I didn't say cooler water adds oxygen. Cooler water holds more oxygen than warm because there are more molecules in it. In cool water, molecules bunch together and don't escape very fast. This is why you want to keep the tank water on the cooler side to maintain a better oxygen level for the fish. Or, you add an air stone attached to an air pump to agitate the water and mix in more oxygen. Again, this is why you want to change a lot of water weekly. The action of the water splashing into the tank mixes oxygen into the water.

Hope this explanation helps.

Old
Thanks, mate!

Well! Did a vacuum/test/ about 50% water change today and got slight nitrates. Not quite 5 but not as pale as last week. Considering all the algae I cleaned last week and how much Sunny has eaten, I'm not surprised!
 

Joyceheatherington

Member
Nicely done exciting!
 

AvalancheDave

Member
oldsalt777 said:
I would recommend performing the large water change weekly. The reason is because water loses its ability to hold oxygen in a matter of a few days due to it constantly running through a filtering system. Minerals are also changed because of their exposure to oxygen and being used by the fish and plants. If you could test the oxygen and minerals in the water, you'd notice changes every day.
I have a dissolved oxygen meter (two, actually) and haven't noticed this.
 
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TheeLadyG

Member
AvalancheDave said:
[QUOTE="oldsalt777, post: 4124554, member: 67823"I would recommend performing the large water change weekly. The reason is because water loses its ability to hold oxygen in a matter of a few days due to it constantly running through a filtering system. Minerals are also changed because of their exposure to oxygen and being used by the fish and plants. If you could test the oxygen and minerals in the water, you'd notice changes every day.
I have a dissolved oxygen meter (two, actually) and haven't noticed this.[/QUOTE]Ok I'm glad to hear this, I'm actually considering trying to contact some water scientists to confirm/deny. I'm an inexperienced fish keeper but I do know a thing'r two about chemistry and biological systems.
 

Skavatar

Member
informative read

wastes (nitrogen) is one of the factors in reducing O2 concentrations in water. pretty much why we do weekly water changes, to remove the Nitrogenous compounds.

this one is about saltwater, but still informative, talks about specific gravity.
 
  • Thread Starter

TheeLadyG

Member
Skavatar said:
informative read

wastes (nitrogen) is one of the factors in reducing O2 concentrations in water. pretty much why we do weekly water changes, to remove the Nitrogenous compounds.

this one is about saltwater, but still informative, talks about specific gravity.
Right Ok so according to what I'm reading IF you have a system with no water movement and the water is deep enough then bacteria can use up the oxygen.

If you are oxygenating your water with good movement then that oxygen is getting constantly replenished, and the nitrogen is going to offgas from the moving surface of the water, right? The free nitrogen can't use up all the oxygen if the oxygen is being replenished by means of surface movement and proper flow of water throughout the tank (no dead spots).

...right?

In all the 20 days of no water changes I watched my fish for signs and behaviors that indicated anything wrong. There were none. No surface-dwelling, no breaching, no gasping, red gills, or surface-sucking. They used all areas of the tank.

Please understand I am in NO WAY advocating "no water changes." I do think there is a bit of confusion here concerning the mechanics of the nitrogen cycle and continued water oxygenation.
 

Skavatar

Member
your setup is fine.

as stated in the links, there are many factors affecting the dissolved O2 levels in a tank. most aquarium setups and maintenance that are recommended here are more than adequate. if anyone has concerns there is the option of either a O2 test kit or the more expensive O2 meters.
 

AvalancheDave

Member
Skavatar said:
informative read

wastes (nitrogen) is one of the factors in reducing O2 concentrations in water. pretty much why we do weekly water changes, to remove the Nitrogenous compounds.

this one is about saltwater, but still informative, talks about specific gravity.
That Fishlab site is in serious need of fact-checking. If you know the owner of the site I can provide this service for a reasonable fee. Regardless, nowhere on that site does it explain how the presence of nitrogenous compounds lowers the solubility of oxygen.

Nitrogenous waste itself doesn't reduce oxygen levels unless it builds up to the level that it begins to approach saltwater. I believe sea water has a TDS of around 35,000 ppm. It's going to take more than a few days without a water change for fresh water to even begin to approach the salinity required to affect the solubility of oxygen.

The claI'm that nitrogenous waste measurably lowers oxygen solubility within days after a water change is facially false.

The conversion of ammonia to nitrite and nitrite to nitrate consume some oxygen but since the solubility of oxygen isn't affected, that's replenished from the atmosphere. Levels of ammonia and nitrite in most aquariums are quite low so the nitrogenous compounds oldsalt777 is referring to must be nitrate. Conversion of nitrate to nitrogen doesn't consume oxygen though.
 

oldsalt777

Member
AvalancheDave said:
That Fishlab site is in serious need of fact-checking. If you know the owner of the site I can provide this service for a reasonable fee. Regardless, nowhere on that site does it explain how the presence of nitrogenous compounds lowers the solubility of oxygen.

Nitrogenous waste itself doesn't reduce oxygen levels unless it builds up to the level that it begins to approach saltwater. I believe sea water has a TDS of around 35,000 ppm. It's going to take more than a few days without a water change for fresh water to even begin to approach the salinity required to affect the solubility of oxygen.

The claI'm that nitrogenous waste measurably lowers oxygen solubility within days after a water change is facially false.

The conversion of ammonia to nitrite and nitrite to nitrate consume some oxygen but since the solubility of oxygen isn't affected, that's replenished from the atmosphere. Levels of ammonia and nitrite in most aquariums are quite low so the nitrogenous compounds oldsalt777 is referring to must be nitrate. Conversion of nitrate to nitrogen doesn't consume oxygen though.
HI Dave...

Actually, if you recall your chemistry classes, oxygen is reduced in the presence of nitrogen in the air. Could be in the form of ammonia, nitrite or even nitrate . Nitrogen is in tap water, about 10 parts per million, not much. But, there's more in the air, about 20 percent. When you fertilize your plants and the fish do their business in the water, there's even more nitrogen produced, so oxygen is reduced even more. This is why you need to remove and replace most of the tank water weekly. The water change action adds oxygen to the water and the dissolved nitrogen is removed by removing the old, toxic water. The nitrogen that's left in the tank, is diluted to a safe level in all the new, treated tap water.

Old
 

AvalancheDave

Member
oldsalt777 said:
Actually, if you recall your chemistry classes, oxygen is reduced in the presence of nitrogen in the air. Could be in the form of ammonia, nitrite or even nitrate . Nitrogen is in tap water, about 10 parts per million, not much. But, there's more in the air, about 20 percent. When you fertilize your plants and the fish do their business in the water, there's even more nitrogen produced, so oxygen is reduced even more. This is why you need to remove and replace most of the tank water weekly. The water change action adds oxygen to the water and the dissolved nitrogen is removed by removing the old, toxic water. The nitrogen that's left in the tank, is diluted to a safe level in all the new, treated tap water.
I'm pretty sure that wasn't taught in chemistry.

Ammonia, nitrite, and nitrate aren't the same thing as nitrogen gas. Even if they were, nitrogen gas can't build up in water open to the atmosphere unless produced at an extremely rapid rate, e.g., connecting a nitrogen tank to an air stone.
 

oldsalt777

Member
AvalancheDave said:
I'm pretty sure that wasn't taught in chemistry.

Ammonia, nitrite, and nitrate aren't the same thing as nitrogen gas. Even if they were, nitrogen gas can't build up in water open to the atmosphere unless produced at an extremely rapid rate, e.g., connecting a nitrogen tank to an air stone.
Dave...

I'm talking about the dissolved nitrogen in the water from the fish and plant waste. This needs to be removed every few days to keep the fish healthy. An elevated nitrate level will certainly decrease oxygen in the tank water and as we know low oxygen levels in the tank water will have a negative affect on the fish's immune system.

Old
 

AvalancheDave

Member
oldsalt777 said:
I'm talking about the dissolved nitrogen in the water from the fish and plant waste. This needs to be removed every few days to keep the fish healthy. An elevated nitrate level will certainly decrease oxygen in the tank water and as we know low oxygen levels in the tank water will have a negative affect on the fish's immune system.
Nitrogen is a gas above -346 degrees F. Dissolved nitrogen in water is going to gas off into the atmosphere.

How much nitrate does it take to affect oxygen solubility?

At 77F, an increase in salinity from 0 to 2 ppt will decrease oxygen solubility by 0.1 mg/L. That means 2,000 ppm of nitrate per day to produce a measurable drop in oxygen solubility.
 

Skavatar

Member
about 4 weeks after using Pond Matrix 0,0,0 (in a SunSun 304B canister)
it has been 2 weeks since my last 50% water change on this 150G stock tank patio pond. before the Pond Matrix it would be 10-20ppm after 1 week.

the phosphate test (Pond Master Test Kit) was murky/cloudy but the picture looks even worse, but its at .25ppm


full.jpg
 
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TheeLadyG

Member
Skavatar said:
about 4 weeks after using Pond Matrix 0,0,0 (in a SunSun 304B canister)
it has been 2 weeks since my last 50% water change on this 150G stock tank patio pond. before the Pond Matrix it would be 10-20ppm after 1 week.

the phosphate test (Pond Master Test Kit) was murky/cloudy but the picture looks even worse, but its at .25ppm


full.jpg
Oh dude that's awesome! I seem to be holding steady at 5ppm nitrates week to week now, but I think it's because my fish keeps chomping on all the algae I'm trying to grow haha
 

angelcraze

Member
Thanks TheeLadyG and Skavatar for your results. Seriously considering switching to Pond Matrix or BioHome too. I have a 120 gallon that accumulates nitrates quickly, been trying different things for months, I got them down with soil in the substrate and more stem plant and plants growimg emersed, but would like to try getting them down more. I thought a canister filter would have too much flow, but worth a try I see.

Maybe I'll try it in a second canister or switch out slowly so I don't lose my cycle.
 

Rick bose

Member
Congrats. I wish you good fortune for your fish-keeping experience in the tank.
And good job on cycling the tank.
Wish you a wonderful fish-keeping experience ahead.
Keep us posted.
 

MomeWrath

Member
Interesting thread. Being that I was at best a casual aquarist before my reefkeeping period, most of my real chemistry-type learning about aquariums comes from the salty side...
So it kept popping into my head as I was reading this, the growing use of "Algae scrubbers" for nitrate control in reef aquariums. Could it be that the algae-covered wall is sort of acting as a nitrate sponge? In an algae scrubber, you create an environment favorable to algae growth (usually a bubble wall in a closed box with a light) and then remove the algae to physically remove the fixed nitrate from the tank. I always let my back wall grow as it pleases.
 

angelcraze

Member
Yep, considered an algae scrubber too, they really work! But I didn't like the look of one built on my 'showtank' and I don't have a sump. Agree, the algae wall is using up some nitrates, but she saw them go up as she cleaned them. So def was helping out using them up, but I was still hoping the Bio stuff was doing something. I just need a little more help. It can only grow so much anaerobic bacteria to process so much nitrate.

My 90g has acheived a complete cycle for years with a deep soil substrate. No nitrAte with 8 angelfish, 3 BN plecos. Lots of plants, but plants alone don't complete the cycle in my 120 gallon with angels, 3 GBRs and 1 BN pleco. So there's something to it.
 
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TheeLadyG

Member
Magicpenny75 said:
Interesting thread. Being that I was at best a casual aquarist before my reefkeeping period, most of my real chemistry-type learning about aquariums comes from the salty side...
So it kept popping into my head as I was reading this, the growing use of "Algae scrubbers" for nitrate control in reef aquariums. Could it be that the algae-covered wall is sort of acting as a nitrate sponge? In an algae scrubber, you create an environment favorable to algae growth (usually a bubble wall in a closed box with a light) and then remove the algae to physically remove the fixed nitrate from the tank. I always let my back wall grow as it pleases.
Yeah, I'm certain the algae is keeping my parameters steady. I don't have the amount of Biohome they say you need for proper denitrification, I reckon it's working in tandem with the algae. My last few readings have been around 5 (I clean about every 10 days or so). I've been upping the food to try and put some weight on my fish that needed surgery. My low stocking surely goes a long way as well!
 

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