High Nitrates

[sassie1973]

HELP.......... i need an expert opinion. ok, so a 125g tank holding about 30 small to medium fish (pseudos, sm parrot, sm JD, one plum, convicts,... you get the idea) anyways, came in tonight, fish were acting lethargic, staying close to bottom. started an immediate water change (last one last week) while checking levels. my ammonia was 1.0 and nitrites were at 0. but my nitrates were over 100. did a 50% change and my ammonia dropped to 0. so i did another 25% water change and still ammonia and nitrites are 0 but my nitrates are still over 80. any ideas? thanks in advance

sassie

[sassie1973]

oh and btw, the fish now have color back and are swimming around instead of "laying" on bottom of the tank

[mnemenoi]

I'd suggest testing the water you are adding during the water change, it can have high nitrates already. Also try swapping your filter material, they can become Nitrate factories. Thoroughly vacuum the substrate, any detritus there can add to it. Consider adding some plants if the problem persists, they take in Nitrates and can be useful in their control. I have found Water Lettuce and Hyacinth to be great at both and nearly impervious to the fish. You could also consider adding a bag of Purigen or De-Nitrate to the filter to assist in controlling the levels in the future.

[Mzungu]

That's odd that you got an ammonia reading of 1.0 before the water change. But I agree with what mnemenoi said - try testing the water out of the tap to see if it's got any ammonia or nitrates. That can really mess up your water changes when you're trying to lower nitrates.

[wesleydnunder]

Yep, sounds like your tapwater contains nitates. A 50% partial should yield a post-partial titer of half the pre-partial titer if the tap doesn't contain nitrates. The fact that yours was so high after the partial points toward nitrate in the tap. However, sometimes the color differences can be less apparent to some folks and also the test procedures have to be followed to the letter for an accurate reading. Assuming all was done correctly, your tapwater looks like the culprit. I'd draw a cup, dechlorinate as usual and test after 24 hours for nitrate.

As far as filters being "nitrate factories", and I hear this a lot, the purpose of a biofilter is to eliminate the hazardous product of ammonia and nitrite and result in a much less harmful byproduct of nitrate. Some species can't handle high nitrates, some can. A properly functioning biofilter by nature and function is a nitrate factory. Managing nitrates is easily accomplished.

Mark

[Sea-agg09]

The tapwater in Galveston contains ammonia, so it isn't all that uncommon. I would suggest either adding extra biological filtration to your filter, and maybe make it a routine to add a dose of bacterial supplement when you do a water change. If your fish are not into eating plants, you may also consider putting in a few java ferns in. The plants will steadily eat up the nitrates. I suggest java ferns because they don't require much of anything else.

[black_knight]

I don't know what your method of dechlorination is. Another senario is failing to properly dechlorinate water on larger water changes can kill off you filter bacteria and there will be a spike in amonia (with the die off)and then nitrates (as there is a regrowth/bloom of bact that processes toxic nitrogenous wastes).