My 9 year old oscar just pasted away, but developed cataracks about the size of dimes, never had a fish with so much personality, he could eat a dozen feeders in 15 seconds, but at times , just wanted to swim and rub against ny hand.. after the eye problems he developed left side swim blater. what do you think caused that? perfectly clean 60 gallon tonk with a 110 gallon sponge,no more than 5 to. 10 gallon , vacuum and water changes weekly, depending on how much mess he made. it allways seemed my ph was a little low. i could add a big piece of drift wood and it would lower it more. what is natual that would bring the ph up a little, or what happened?