I HAVE A GREENTERROR that is sick with popey and white stringy poo. I treated him with melafix for around 10 days in a 15gal sick tank. he is now back in my 180 popey healed but still stringy poo. he tries to eat but just spits out the food. im prety sure he got sick because of bad water...low ph but water parameters have improved ph 6.6 everything else is good. is there something more besides water changes that i should be doing?