Hi Tab. Basic guideline for gallon size is 10 gallons of water per inch of shell length (without the curve) per turtle. If you get one turtle say 2", you'd need a minimum of 20 gallons of water. So, your 29 gallon would work for a short while, but as the turtle grows, you'll need a bigger tank. Males can grow up to 9" (90 gallon minimum), females up to 12" (120 gallon minimum).
Do you still have the fish? Turtles will eat anything that moves in their tank, among other things that are small enough to fit in their mouths. That leads us to gravel: use larger river rocks around 2-3" size, scattered on the bottom. Easier to clean, turtle can't eat them, and they like to push them around the bottom.
Whatever size tank you get, you need a filter that filters 2-3 times that amount of water. Canister filters are highly rated on here, a little more costly than over the tank filters. There are extension pieces you can buy for the filter pipe, if you go with the over the tank style.
You'll also need a heater, I recommend the Stealth, make sure you get the correct wattage for the size of your tank.
Lights: You'll need a regular household bulb (incandescent) for heat for basking. You'll need to get a UVB bulb also, compact or flourescent tube. Recommended ones are Reptisun 10.0, Repti-Glo 8.0. You'll also need the lamps for these bulbs. Most people use clip on for the household bulb, and the compact UVB. If you use the tube UVB, you'll need the ballister for the appropriate size bulb. Zoomed basking docks are good and inexpensive for the turtle to bask on. Also, get some plastic plants that are weighted down or suction cup them to the bottom of tank for little turtles to have 'resting' spots while swimming.
Size of Res to get depends on what's at your local pet stores, and what size you want to start out with.
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(I think I went a little crazy with all the info, but I hope it helps!)
