Well ihaven't had this problem but my nitrites were high which is bad for them, i did a small 15% water change and added Stress Zyme and it completely got rid of my nitrites, nitrates, and restored my biologics. This might help.
bacteria live in the filter not the water you need a lot of bio media in your filters which you shouldnt clean otherwise you will clean out your bacteria mwke shure you have correct bio media and let the tank cycle 3ppm is a lot of amonia id do 50 % water changes everyday until there is very little ammonia