Nitrites – When nitrites are present at any level in the pond you need to take it seriously. Nitrites can bind up the red blood cells in fish causing brown blood disease which can be fatal. One sign of high nitrites is the fish gasping at the pond surface.

What can cause a high nitrite level?

All the things mentioned above for high ammonia levels could also cause high nitrite levels. One note is that the nitrobacter bacteria which removes nitrites is much more fragile than the nitrosomonas bacteria which removes ammonia. This nitrite reducing bacteria takes twice as long to develpoe in a new filter and is the first bacteria to die off if you run a strong medication through the filter media. Also, if a filter gets plugged up or is not cleaned often enough, nitrites will build up in the pond even before the ammonia does.

How do I solve high Nitrite levels?

Again, just like ammonia, you want to perform water changes, stop feeding the fish and add oxygen if necessary.


We carry four basic test kits that help you to monitor the four basic parameters of your pond water. These test kits are truly worth their weight in gold.