It is my big discus tank - 450 litres with a 80-100 litre sump and also a cf1200 external cannister filter on it. Nothing dead or missing presumed dead, everything seems okay including my one blue ram in there. I did change the filter wool on the sump on Monday night but that was all. The week before I had to change the motor on my external filter because the other one wasn't running properly - sort of on and off so I discovered.
Perhaps I should rinse out the media in that filter and see if that helps?
I'll test again tomorrow night and if necessary change 30-50% (hubby will be home from work so he can carry some buckets - it was his idea to have discus in the first place, not mine!!!).
Test kits about 2 months old.
What sort of things will the fish do if the ammonia is too high for their liking?