Ive had my 36 gallon tank up and running for about 4 months. Tank was fully cycled after a few weeks using tetra safe start. I have 12 cichlids (4 yellow labs, 4 acei, 4 red zebras) in the tank and 1 pleco. All about 1-2".
Before these high ammonia levels, I did 50% water changes each week and vacuumed once a month. My water levels were always 7.4-7.6ph, 0-.25ammn, 0 NI, 20-40 NA.
About 2 weeks ago I checked the water and the nitrates were between 80-160 (closer to 160 but hard to tell), 0 nitrites and .25ammn. I did a 75% water change and the nitrates were down to about 20.
3 days ago I checked the water and the ammonia looks like its between 4.0 and 8.0!!! Nitrates looked to be around 80-160 again. I changed roughly 80% of the water and checked the levels an hour later. Nitrates were down to 20 but the ammonia was still between 4.0 and 8.0. I added prime to the tank b.c I was worried for the fish.
The next morning I removed all the fish, rocks and decor. I vacuumed the gravel thoroughly making sure to stir up all the gravel and I changed about 90% of the water.
I checked the water today and the ammonia is between 4.0-8.0 again after a vacuum and 90% water change. 7.0PH, Nitrites 0, Nitrates 10.
All the fish are very active (like always) and they are showing no signs of stress. I have 2 HOB filters with carbon filters, fluval foam around the filter intake pipe and aquaclear biomax inserts inside both of the filters. I changed the carbon filters about 3 weeks ago. Ive had the biomax inserts in the filters for about 2-3months. I rinse the fluval foam inserts once a week with tank water to clean them out.
Whats causing this ammonia spike?