It's good you're not starting with softies then, usually recommend people try regular turtles first
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Then, same as any turtles, you can appreciate they need fairly large aquariums, a 4 foot tank would be OK as long as its 2 foot wide. Naturally, you will soon need a decent sized external filter as the turtle produces more waste.
They do spend most time in the water, but what I meant was to the the water very shallow at parts to it can paddle around and stick it's head up easily - they spend quite a lot of time dong this. When young they also like to bury themselves in sand a lot. You can provide a deeper area for swimming if you want but it doesnt seem to stress them not having this.
I would still say that it is necessary to provide a basking spot! They do bask, just not as often as other turtles. For this a piece of wood or smooth slate just big enough for the turtle with a heat bulb above it (not making it too hot!) is fine. Having water running over the basking spot is a good idea to stop it getting too hot.
UV isnt the most important thing in the world, but I would still recommend letting them get as much as possible, since they spend a lot of time paddling in shallow water, a 5 or even a 10% UVB florescent tube will be great. I'd personally go for the 10% and just give a shaded area (a silk plastic or real aquatic plant is good for this).
You need to make sure the water is very clean for these guys, so really no skimping on filtration. They get infections pretty easily compared to sliders. No shart rocks or ornaments should be used. They are also more nippy then older, and most bite if you annoy them at all, so they arent the best for children.