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Discussion Starter · #1 ·
I am running a Fluval FX4 on a 125 gallon African Cichlid tank. Currently have 12 fish including Mbunas, Haps and Peacocks. My nitrates seem to be higher than what I would expect. I do a 50% water change weekly. My nitrates are at about 60-70 ppm each time. A 50% water change only gets me to about 30ppm. I recently started doing water changes every 5th day to keep things under control. I do feed twice per day however. I am considering placing Matrix in my filter to see if that might help reduce my nitrates or at least get me back to a 7 day schedule. Is anybody using Matrix with any success?
 

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I've used it and it's good biomedia, but I don't think it's going to reduce nitrates significantly.

Does your tap water have nitrates?
 

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Discussion Starter · #3 ·
Tap water is fine. I might try Matrix to see if there is any difference. I may also try a larger water change to get my nitrate baseline down to a lower level. Another option is to feed less I suppose.
 

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I'd definitely up the water changes and feed less. Also might try different food. Maybe some Repashy gel or some food with probiotics?
 

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A 125G with 12 fish the size of mbuna shouldn't need more than weekly water changes and 50% should be plenty. Also, bacteria will settle wherever if there is ammonia and oxygen. "Better media" won't make a difference. The easiest explanation is that you are overfeeding - and not just a little bit. This is easy to do, because those fish will beg for food whenever somebody passes the tank, and it is difficult not to give in to them. My recommendation would be to feed once a day, and maybe even cut down the amount per feeding. Also, it is not a bad thing for them to go without food for one or two days every once in a while. For example if I am out of town for a week, it is far better not to feed them, than have somebody feed them who gives too much. The latter can kill the entire tank, the former has never done any harm that I am aware of.
 

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Discussion Starter · #7 ·
Thanks. Half the fish in the tank are 3-4" haps and peacocks with one Venustus about 5". Point taken though. I will reduce the feedings.
 

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I have 10 aquariums. Why is it that 7 that are running on just huge sponge filters have 5-20ppm of nitrates compared to 60-80ppm with the 3 that are running huge 4 tray canisters filled with coarse/medium/fine foam/pinky filter/poly wool/Matrix/Pond Matrix/Marinupure Balls. Not blaming the matrix here, but maybe beneficial bacteria can't hang on well in canisters? All aquariums have about the same ratio of fish to gallons and wc frequency.

Maybe I need to clean these canisters (Sunsun 704B/Eheim 2217) more often? Cleaning about once every 3-5 months, sponges every 2-3 months.
 

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Just a guess but would try upping the maintenance on the canister filters to see if that makes an impact on the nitrate level.
 

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easywolf31 said:
I have 10 aquariums. Why is it that 7 that are running on just huge sponge filters have 5-20ppm of nitrates compared to 60-80ppm with the 3 that are running huge 4 tray canisters filled with coarse/medium/fine foam/pinky filter/poly wool/Matrix/Pond Matrix/Marinupure Balls. Not blaming the matrix here, but maybe beneficial bacteria can't hang on well in canisters? All aquariums have about the same ratio of fish to gallons and wc frequency.

Maybe I need to clean these canisters (Sunsun 704B/Eheim 2217) more often? Cleaning about once every 3-5 months, sponges every 2-3 months.
"Beneficial bacteria" convert ammonia into nitrite and nitrite into nitrate. "Beneficial bacteria" do not remove nitrate, but rather produce it as an end product.
Your water changes remove nitrate and your maintenance can remove waste that will eventually be broken down to become nitrate. It is possible that in your sponge filter tanks you are removing the waste before it breaks down, and in your canister filtered tanks, this waste is accumulating in the canister and has broken down long before you ever cleaned the canister. But probably more significant would be the bio-load of the tank (the combined weight of the fish in relationship to the gallons) as well as the amount of food that is fed to the tank. The Nitrogen originates from the food we feed and the fish produce ammonia not only from fish waste, but also respiration. And larger fish produce a lot more ammonia from both respiration and waste.
 
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