Planted Tank Enthusiast
Join Date: Oct 2002
Location: Minneapolis, MN
wait wait wait.... Plants use all forms of nitrogen in the aquaria, ammonia, nitrite, and nitrate. But...this is how the cycle works (without plants). First, fish produce ammonia (toxic to fish). Then, bacteria process the ammonia into nitrite (VERY toxic to fish). Then, another bacteria processes the nitrite into nitrate (harmless to fish if in small amounts). Then, you do water changes to make sure there aren't too many nitrates.
In a planted tank, there are still some bacteria which do the same as above, but there are much less of them.
Why? Because plants prefer to use ammonia as their source of nitrogen. So, there is less "food" for the first bacteria, which means there is less food for the second bacteria. But, any ammonia that the first bacteria gets will get processed into nitrite, which plants will also use. So, now there are even less nitrites for the second bacteria. So in a planted tank, you have a LOT less bacteria than in a normal tank.
So...if your tank has lots of nitrites, it is NOT cycled. You need to have 0 nitrites before it is cycled. Hope this clears things up!