Hey, folks. I've been in the process of gradually upgrading a turtle's habitat, and I'm mostly here to eyeball other people’s setups and get ideas.
TL/DR version: Boyfriend bought small peninsula cooter (I think ... goal was to get a SW Florida native species, naively thinking a native could be released) for his then-5-year-old daughter, four years later turtle is much larger and formerly sufficient habitat was far from adequate.
So this all started because Fifi (this is what happens when 5-year-olds name turtles) was in a 40-gal tall tank, but it was only able to be filled about 2/5 deep because of basking rock height. First, I started cleaning the filter more often. Then I added a second filter so there would be water flow/filtration on both sides. Then there was a tank sale at Petco and I got a 40-gallon breeder tank for $40, figuring the basking setup would still limit the height but hey, at least she'd have more front-to-back space in the tank.
Having determined that the two small in-tank filters were still woefully inadequate, I recently bought a SunSun canister filter, which we preliminarily set up last night. Today, I picked up cork bark and jungle vine, with which I am hoping I can create a supported floating-ish dock, so at least she'll be able to swim under it and it won't be taking up valuable water space. Next, my goal is to create a plexiglass structure to inhibit escape, so the tank can be filled more or less completely, with the cork bark dock (if it works out) raised to the height of the tank.
I realize this tank is still *way* too small (she's probably about 9 inches SCL), but right now I'm limited in what I can provide both due to space limitations in his apartment and $$, so I'm trying to make the most of what I've got to work with. Even if I found a fire-sale Craigslist deal on a 100-gallon tank, I haven't the faintest idea where I would *put* such a thing ... or how I'd even get it from point A to point B, for that matter!
Ultimately, there may be a pond-building project in the future (at my house, or perhaps his parents’, in South Carolina).