Hey sorry for the late reply!
1) 60 Gallon Tank, about 2/3rds full
2) I have an external Fluval 306 filtration unit
3) I'm not too sure, I recently had a massive clean out of the tank as it was getting a bit dirty, I basically opened my filtration unit and cleaned out the muck, I think it had been bunged up for a while and was making the tank dirty. I made sure to only clean with tank water and then I took all obstacles out of the tank, now it is very clean and has nothing in apart from the basking platform.
4) I feed them both on a diet of frozen bloodworms, mixed turtle food (fish, spinach other various essentials) and small frozen fish every 3/4 days
5) The water is extremely clean now, but I fear my filter had not been working properly so I cleaned it out, I think maybe this has had something to do with his eyes?
6) I dechlorinate all water with product before going into the tank to account for dropping water levels.
7) Yes he has both UVA & UVB bulb in the middle of tank and above basking platform.
He manages to get his eyes open in the water, sometimes very easily but sometimes one might be open and the other takes a little while
I will post some pictures soon, there isn't any discolouring around his eyes, but he is spending a lot of time asleep on the basking spot, and I am worried his shell is becoming very dry and maybe a bit flaky - this goes away when he is in the water but it seems like he is taking ages to get rid of any shedded schutes!
Thanks