He is 5 years old. The water temp is around 72-73 F and the basking dock is around 84 F. I feed him 10-15 pellets (this ------- big) every second day and pure, lettuce-made jello shots on the days in between.
A little bit of background info: I rescued him from my aunt, who was keeping him in very poor, cold and un-lighted conditions. His shell is almost 5 inches.
I had to keep him in a 25g tank until I got moved into my new place, so that I could set up a 75g tank I bought for him. The filter that was with the 25g was really shitty so, even though I was doing 50% water changes every week, the water wasn't that great. I was thinking maybe water quality was making him shed.
Now he's in the 75g with a Rena XP3 Filter and the water is crystal clear. I also got the water tested, and the pH was a little high but I was told a 10% water change would help this.
What can I do to make him stop shedding his skin?

