In your first post you indicated your nitrate test read <50ppm???I have a 75 GL with a FX5 filter. I never had nitrites nor nitrates. The Acara is too shy and always is hiding behind the wood, I think he hit the eye and get infected, all the other fishes are really healthy, shining and hungry the whole day, If the water conditions were poor, I will notice some other symptoms in the rest of the community.
This is how you answered the questionaire
Have you tested your water?Yes
If yes, what is your ammonia?0
If yes, what is your nitrite?0
If yes, what is your nitrate?< 50 ppm