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FAQs on Freshwater Quality involving Nitrites: Science

Related Articles: Nitrites in Freshwater Aquariums, Nitrates in Freshwater Aquariums, Biological Filtration, Establishing Cycling, Freshwater Filtration, Know Your Filter Media, A Concise Guide to Your Options by Neale Monks, Setting up a Freshwater Aquarium, Tips for BeginnersWater Quality and Freshwater Aquariums

Related FAQs: Importance, Measure, Sources, Control, Chemical Filtrants, Troubleshooting/Fixing, & Ammonia, FW Nitrates, Freshwater Nutrient Cycling, Establishing Cycling 1,


Uncycled tank with nitrites -- reading, water changes and live bacteria are needed -- 06/28/07 Hello everyone. <Hi Melissa.> I purchased a 10-gallon a little less than a month ago. I conditioned the water, and let the filter run for 3 days. I then purchased a Glo fish as my starter fish. Not knowing much about the nature of schooling fish, or the nitrogen cycle, I purchased two more GloFish shortly thereafter. To make a long story short, they all died. So, I purchased one more GloFish and left him in there by himself for about two weeks. Feeling confident with the stability of my tank, I then purchased two black Lyretail mollies. Unfortunately, they were picking on the GloFish, so he has been removed. The mollies are looking great, so now to my question. I do water tests frequently, and a very recent test showed that my nitrites are high (about 2 ppm) and my nitrates are just slightly lower (around 15 ppm). I'm not sure how long the cycle takes to complete (I've heard 4 to 6 weeks) but I do know that nitrites are very dangerous. However, everything else (ammonia, ph, etc) is at its appropriate level. I have good filtration, plenty of salt to suit them, and some live plants which were added two days ago. I also did a 15% percent water change just a few days ago to try to reduce the nitrites, but they have not come down at all. <A 15% water change will decrease nitrites by 15%. In your case that's not even measurable with the standard tests. To decrease them to 0.4 change at least 80%.> Are the high levels to be expected, if the cycle is almost complete? <No. Your cycle is complete when the nitrites have spiked and fallen back to 0. Only then the first fish should be added. Personally I do not like the idea of fishes in an uncycled tank. Live bacteria from the filter of a running tank or the LFS fridge (BioSpira) can be used to instantly cycle a tank. > Or is this a serious problem that needs addressing? <Additional problems cannot be excluded now. Overfeeding is one possibility. Only feed as much as is eaten in a few minutes. If the nitrites aren't absent within a week consider additional factors that could prevent your tank from getting properly cycled. In the meantime read some more on the nitrogen cycle and the needs of the fishes you want to keep. Lots of information as well as a handy search panel are available at WWM.> Again, the mollies don't appear unhealthy in any way, and I would like very much to keep them healthy, so your help would be immensely appreciated. <Some types are quite hardy. Anyway, do large water changes and possibly get some bacteria from a running tank to minimize any permanent damage due to the exposure of toxic water conditions.> And depending upon your response, I would like to add a couple more of the little guys, so let me know if this is a safe decision. <Too early. Wait until the nitrites are 0 and be sure to read before you purchase.> Thank you so much for taking the time to read my ridiculously long question and I look forward to your reply. <Hope that helps. Marco.> Sincerely, Melissa.

Lowering Nitrite 8/3/05 How  harmful is a high nitrite n02 and how can I lower it. < Ammonia is the most toxic form of fish waste. It is then converted by bacteria to a less toxic form of waste called nitrite. Bacteria then convert it one more time to an even less toxic waste called nitrate. In a new tank it takes about 2 weeks for the bacteria to get established and convert the ammonia. In another two weeks the bacteria are then established to convert the nitrite to nitrate. Different fish have different tolerances to nitrite. Some FW riverine species have zero tolerances while others don't seem to be affected at all. The toxicity is also affected by the pH. Lower pH's make these compounds less toxic. Reduce nitrites by reducing the waste. Don't overfeed, vacuum the gravel and clean the filters. Some chemicals will actually tie up nitrites. I am not too sure what the long term affects will be. Go to Marineland.com and check out Dr. Tim's Library for lots of articles on nitrification.-Chuck>

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