for like 3 weeks my fish have been going from one sickness to another....first they had ich so i treated for ich then before i got to put in the carbon again i came home to my fish and they were covered in white stuff almost like when you peel from a bad sunburn so i treated again with maracyn. they looked good after too treatments now my jack dempsey and flowerhorn are puffy and the jack's eyes are popping out i don't know what to do i've been doing 50% water changes like twice a week i'm afraid to put more medicine in i don't want to hurt the fish by adding stuff all the time. i have a 72 gallon bowfront i stopped medicating put in chemipure in my filters and checked my parameters my ph is 6, no ammonia or nitrites and my nitrates are 30-40ppm. i can't seem to get my ph up and i don't know what to do anymore some advice would be appreciated!!!! i'm clueless!!!