Originally Posted by Burd
I haven't tested the water but the ammonia alert thing I have on the tank is between .05 and <.025 so I have to assume at least he's fine there. The other fish also seem fine.
The in-water submerged ammonia sensor reads UNBOUND ammonia, it does not read the actual level. You can have an actual level of 7.0ppm but using prime have that little sensor only read light green-yellow. If that sensor is not cold-and-bold yellow you have an ammonia problem that must be immediately addressed.
High ammonia levels can stall the nitrate cycle because the bacteria that eat the ammonia go to sleep until the ammonia goes away.
If you use anything that says it makes ammonia "safe" and that sensor goes off of yellow you should immediately start water changes as if your bio-filtration died.
The API liquid test kit is the simplest to use to measure ammonia, store it in cool room temp.