Nitrite Level Very High

Question
Hi Nicole
How are you? Happy New Year. I am starting all over again on the Fish tank for the New year... Yes, I lost almost all of it but a couple of CatFish!! Bought 4 new Danio's tonight and put them in... Checked with the Strips I have and looks like the Nitrite level is around Stress 3.0 to 5.0 ppm if I am not wrong. History - Long story short, I lost my betta, 2 guppy, 1 danio, 1 catfish due to the nitrite poisoning. Changed 25 - 30% every other day and they all died. Frustrated I changed 100% of the tank and added the catfish. Checked with the strip the nitrite and nitrate showed SAFE. Added some flakes couple days back to start the Bio cycle but looks like it has backfired!! :(... Recently changed the TopFin filter to a filter with Bio Wheel (this was when the Guppy and Danio were dying). As of tonight, the nitrite is back to what I did NOT want it to be. I do not know what is going on. Your help is highly appreciated. Thanks a TON!!

Have a Nice day.

Cheers
Ram

Answer
Hi Ram,

Happy new year to you, too! Sorry to hear about your tank troubles. Sometimes it does seem like the cycle takes longer than we like to get established. 2 weeks is about the norm, but 3-4 weeks is not unheard of either. Unfortunately, adding a pinch of flakes to feed the bacteria is not effective if you only did it for a few days. You need to sit and watch an empty tank for a couple of weeks! Feeding the tank flakes, or leaving a bit of cocktail shrimp in the water, is an effective way to "fishless cycle" (you can Google that for more info) but it takes lots of patience, and testing with a kit every day or every other day.

Now that you have fish in there, the best thing to do is to keep doing daily water changes (I'm not sure what sized tank you have, so not sure what to recommend - probably 25% or so) and add some sort of neutralizer to the new water so that the nitrite is in usable form for the beneficial bacteria, but is not toxic to fish. Seachem's Prime and Kordon's Amquel+ will both accomplish this, just look for a dechlorinator or water conditioner that says it detoxifies chlorine and chloramine, and can neutralize ammonia in an emergency. Prime can accomplish this by using a double dose (4 drops per gallon instead of 2 drops per gallon). If you can find Prime, it's what I'd recommend.

After a couple of weeks, everything should be settled down. The bio-wheel filter will definitely help, since now when you change the cartridges you won't be throwing away all the beneficial bacteria - you'll still have it in the bio-wheel, which you should never replace and shouldn't have to clean...it works better if it's dirty.

Depending on what kind of catfish you have, a little salt might help with the nitrites. Coydoras really don't like salt, nor do plecostomus ("catfish" can mean all kinds of different fish) but there are some catfish more tolerant of salt than others - research the individual catfish you have to find out. Salt adds slime coat to the fish, and makes the effects of nitrite less severe. I would add 1 tablespoon per 5 gallons of salt (and by this I mean non-iodized salt, such as kosher salt or sea salt, but "aquarium salt" works too - it's just more expensive and is the same thing as kosher and sea salt!) while the tank is still cycling. Once everything settles down, you can do water changes as usual and not add any salt from then on.

These are websites I always recommend for research:
http://freshaquarium.about.com
http://www.wetwebmedia.com

I hope that helps! Take care.
Nicole