acceptable levels

[SeanTrollope]

what are the acceptable levels for NO2 in a tank. obviously 0 is what we aim for but at what point can we not have to worry about our fishes well beings.

 

[Byron]

I am assuming you are referring to nitrite, technically written as NO-2 [NO2 is technically nitrogen dioxide] as most of us tend to ignore the minus sign.

Fish readily absorb nitrIte from the water and it combines with the hemoglobin in their blood, forming methaemoglobin. As a consequence, the blood cannot transport oxygen as easily and this can become fatal. At 0.25 ppm nitrite begins to affect fish after a short period; at 0.5 ppm it becomes dangerous; and at 1.0 ppm it is often fatal.

Nitrite should never test above zero in any aquarium with fish. Even a short exposure to nitrite can have permanent and irreversible detrimental effects on fish.

Byron.

 

[SeanTrollope]

thank you

 

[eaglesaquarium]

If you are dealing with a nitrite spike, water changes will remove it, but also (depending on the fish you have) a salt treatment can protect the fish, until the nitrite is dealt with by the bacterial filtration.

http://www.fishforums.net/threads/rescuing-a-fish-in-cycle-gone-wild-part-il.433778/

The linked thread tells you everything you need to know about dealing with nitrite.

 

[SeanTrollope]

thanks