Getting there...
I have had my girls, Sam and Ella (mature RES, 9" and 7"), for about 11 weeks now.
While they are still in the 55-gallon tank that I acquired from their previous owner, that is about all that remains the same.
They had been woefully neglected, living in a 20 gallon tank without proper lighting or a heater or ever having eaten anything other than not so great quality pellets, so that 55 gallon tank seems like paradise to them still. I am looking for a 150 to 200 gallon tank, but already have acquired the outdoor pond and fencing that will go in late next spring so they can be outside girls during the nice weather and have an aquarium home only during the winter.
Thanks to all the info and help I found here, the girls have a 265 gph canister filter with UV and biomedia (Which won't do for a bigger tank, but we will deal with that when it happens, lol.) with a 300-watt in-line heater. I built a framework of PVC pipe that is 19" length and now down to 10" height. It is topped with slate to provide them with a shallow water area, and also serves to provide them a cave to hide in and also allows them to still be able to swim the entire length of the tank.
I have a 100 watt basking/UVA/UVB and a 75 watt basking lamp in a double fixture. That is about the limit of what I can do until I contract the electrician to do some additional wiring. The basking area is, at this point, laid up rocks at one end of the slate platform. I am studying different out-of-tank basking area constructions so that I can increase the depth of the water to the full height of the tank. It is presently about 15" deep... barely enough to make sure they don't drown. Woefully inadequate for their size, but vastly improved from their former living conditions. And, a cork bark dock attached to one corner to allow an additional out of water area. The substrate is still bare at this point as the biofilter isn't optimal yet, but like everything else associated with the girls, it's getting there.
They are able to swim freely for the first time years, and their demeanor is greatly changed from when I first brought them home. They are no longer panicked and skittish about any type of activity in their vicinity. They don't splash and claw frantically when they go for a swim; they glide... just like the loved and well-cared for turtles that I see in those YouTube videos!! Ella greets me every morning when I wake up and every evening when I get home from work. She will scramble to whatever area of the tank I am near so that she can look me directly in the face. She is the more social of the two at this point, but Sam is coming around. Sam will continue to hang out in the basking area rather than going for a frantic dive back into the water when I approach the tank. She is even beginning to come near to see what I am doing when I am in the vicinity of the tank rather than looking for the furthest point away from where I am. Occasionally, she will come and look me in the face.
They are learning to enjoy eating greens and seem to like the red leaf lettuce the best. Bloodworms and shrimp are occasional treats. I have had the floating calcium bars in the tank as they had been so poorly fed and kept without UV for years. Their lamps are on timers to approximate seasonal light.
I will get some photos of our current set-up and post them when I can figure out how to upload and post.
We still have a long way to go, and I still have much more to learn, but they are happy and much less stressed. And, I think they enjoy watching "cat TV" as much as the cats enjoy watching "turtle TV." 
While they are still in the 55-gallon tank that I acquired from their previous owner, that is about all that remains the same.
They had been woefully neglected, living in a 20 gallon tank without proper lighting or a heater or ever having eaten anything other than not so great quality pellets, so that 55 gallon tank seems like paradise to them still. I am looking for a 150 to 200 gallon tank, but already have acquired the outdoor pond and fencing that will go in late next spring so they can be outside girls during the nice weather and have an aquarium home only during the winter.
Thanks to all the info and help I found here, the girls have a 265 gph canister filter with UV and biomedia (Which won't do for a bigger tank, but we will deal with that when it happens, lol.) with a 300-watt in-line heater. I built a framework of PVC pipe that is 19" length and now down to 10" height. It is topped with slate to provide them with a shallow water area, and also serves to provide them a cave to hide in and also allows them to still be able to swim the entire length of the tank.
I have a 100 watt basking/UVA/UVB and a 75 watt basking lamp in a double fixture. That is about the limit of what I can do until I contract the electrician to do some additional wiring. The basking area is, at this point, laid up rocks at one end of the slate platform. I am studying different out-of-tank basking area constructions so that I can increase the depth of the water to the full height of the tank. It is presently about 15" deep... barely enough to make sure they don't drown. Woefully inadequate for their size, but vastly improved from their former living conditions. And, a cork bark dock attached to one corner to allow an additional out of water area. The substrate is still bare at this point as the biofilter isn't optimal yet, but like everything else associated with the girls, it's getting there.
They are able to swim freely for the first time years, and their demeanor is greatly changed from when I first brought them home. They are no longer panicked and skittish about any type of activity in their vicinity. They don't splash and claw frantically when they go for a swim; they glide... just like the loved and well-cared for turtles that I see in those YouTube videos!! Ella greets me every morning when I wake up and every evening when I get home from work. She will scramble to whatever area of the tank I am near so that she can look me directly in the face. She is the more social of the two at this point, but Sam is coming around. Sam will continue to hang out in the basking area rather than going for a frantic dive back into the water when I approach the tank. She is even beginning to come near to see what I am doing when I am in the vicinity of the tank rather than looking for the furthest point away from where I am. Occasionally, she will come and look me in the face.
They are learning to enjoy eating greens and seem to like the red leaf lettuce the best. Bloodworms and shrimp are occasional treats. I have had the floating calcium bars in the tank as they had been so poorly fed and kept without UV for years. Their lamps are on timers to approximate seasonal light.
I will get some photos of our current set-up and post them when I can figure out how to upload and post.