Nitrate problem

[Amber]

My fiance has a 75 gallon tank that has been established over a year now that in the past 2 weeks has been destroyed. All of his damsels and his clownfish died, and we almost lost his snowflake eel before I transferred him to my tank. They all died suddenly within 3 days of each other. I tested his tank and his nitrates were at about 40 ppm. I did a 50% water change and it is still at about 10-20 ppm. He also has a pH of 8.0. He has a Whisper power filter and a large biowheel filter and a powerhead. What could have been the problem? Is the pH too low (should be 8.2?)? Or are the nitrates the problem? We already added StressZyme but it did not help. I tested the ammonia and nitrite also but both were normal. Any help would be appreciated. Thanks!

[Doug1]

Amber the reading of about 20 is pretty much ballpark after a 50% water change.Fish only tanks with the type of mechanical filtration you describe will suffer elevated nitrates over time without adjoining anoxic areas to foster the growth of anerobic bacteria that convert nitrate back into nitrogen gas. 40 isn,t horribly high for a fish only, though more frequent water changes will keep it to 20 or less which would be better. The suddennes that the problem set in makes me tend to suspect and environmental toxin from out side the tank. HAve you changed source water or added anything new to the tank? Additive wise. Careless hand in tank that have lotion or household cleaners can be deadly to a marine tank.

[ 03-21-2001: Message edited by: Doug1 ]

[FishDaddy]

Hi Amber,
Sorry about the losses.
Does the tank have a sandbed or live rock?
The Nitrates are symptomatic of other problems in the tank. As Doug suggests, look back at the days preceding the deaths to see if there was anything that could have been introduced accidentally or any other changes that occurred.
Sometimes fish deaths are due to poor oxygen exchange from lack of surface agitation. The filters you have should be doing that though. Has there been a power outage or other shutdown that could have deprived the tank of oxygenation?
How big is the Snowflake and how many fish were in the tank? Bioload could be a factor.
Water changes are good but I would avoid additives that may just compound the problem.
HTH
Dick

[wagnutz69]

IMO, I doubt it was the nitrate levels that killed your fish. Ihave a 55 gallon, that is heavily overstocked (fish only). This is because before I found this BB I listened too much to the LFS's. The nitrates in that tank are well above 200!!! and will not come down. I am tearing it down this weekend, currently building a new tank for my fish. I have a 20" Snowflake, 2 triggers, a clown and a yellow tang that aren't showing any signs of distress. Eel has been in the tank for 2 yrs, and continuously grows, same with yellow tang/clown. Triggers over a year. This is the only tank that has not lost a fish, and the water chemistry is the worse. I'd check for other contaminents, something that would have happened suddenly. Check to see if there are any chemicals/other that have contaminated. Also, check for an electrical current, I had a mild one in my 58 from a heater, and lost some/but not all fish.... Also, the fish may not be getting enough oxygen, is there a great amount of current beaking the water surface? I have also suffered from that problem... I hope everything turns out in the longrun for you.


WAGZ