http://imgur.com/FJP9WuT
(Sorry for the blurry photo) As you can see, he is roughly 6 inches long. Not much else to say about it.
http://imgur.com/eI85V6w
This is what is worrying me the most. His shell is gray/whiteish in a lot of areas. His shell isn't soft or has holes. The only thing i know that is wrong with it is pyramiding.
http://imgur.com/E8NL04X
This is his filter. It's rated for 50 gallons and he's in a 20 gallon tank, but his water is green and not clear.
http://imgur.com/dog4hX0
This is the whole setup. I have nice flat rock on the right and a floating dock on the left. I moved his heat lamp from above the floating dock because I lost a piece of the arm for it and it's way to close to the dock and I'm worried about burning the poor guy. The tank is a 20 gallon tank and has roughly 11 gallons of water in it. He spends most of his time chilling on the flat rock under the heat of the lamp or attempting to climb the glass and escape. He also likes to swim into the glass either at me ( which I assume is him begging) or next to the filter (which I assume is him trying to escape again) There's a goldfish in there names Jeffery who was supposed to be food, but Mr.Turtle left him alive and now he eats whatever floats around. With my next paycheck I'm going to replace the filter with a canister filter that can hopefully stop his tank from getting green. I'm also thinking about building him a better floating dock, since he has trouble climbing onto that one and staying on it. I used to feed him a handful of pellets 3 times a day (because that's what I was told to do) but they would get sucked into the filter and would turn the water green (like it is now) so I started feeding him just shrimp 3 times a day, only 4-6, and then I learned that too much protein can kill them and that you're only supposed to feed them once a day to once every 3 days! I feel so bad for him.
There is rocks at the bottom of the tank. I see him put them in his mouth, but they're the size of his head so he can't eat them. I put them their because when he would try and 'walk' on the floor he would just slide and I felt bad that he had trouble moving around, so I put them in there. I'm thinking about replacing it with some sort of rubber flooring/mat so he can still have the grip, without the choke hazard and the substrate.
Well, that's really all the information I have to give. Thank you for anyone who can provide information to help me make sure this guy gets the care he needs. This is my first pet and it was an unexpected one (person who gave him to me had a parents that was forcing her to get rid of him, so I took him in last minute so he wouldn't be released in the wild since we live in Florida and they're highly invasive)
Thanks again!
TL;DR - I want to make sure I have the right setup for my pet turtle. I'm going to replace the filter with a canister filter, I'm going to make a better sunbathing dock for him, and I'm worried about his Shell color. Anyone who can help me will be thanked a ton. Pics above. Thanks again.

