Turtle Habitat Design

[Niranut]

We have two red eared slider turtles, which we bought back in April of this year. When we got them, I knew nothing of how to care for them so just did what the saleswoman told me... I put them in my 30 in. fish tank with all of my fish, and fed them special turtle food twice daily. And they seemed to be doing really well and growing a thriving and such. But now they're pretty big-- one is about 6in from one end of the carapice to the other, and the other one is a little bigger at about 8in. We attached some pottery pieces to the top of the tank so they can climb up out of the water and hang out up there. But now that they're so big, only one can do this comfortably. The bigger one just kind of hangs off of it.

I looked at getting a bigger tank just for the turtles, and had forgotten how expensive the tank setups are. It's about 3,000 baht for a 36 in. tank with the stand, cover, light, filter, & pump. And while they will have their own space, it's not really enough for two turtles who may get a bit bigger yet.

So I was thinking of getting one of those big plastic tubs (maybe 400-600L, about 1.5-2m across) and setting it up to be an outside turtle habitat. That way the turtles would have much more personal space for about the same price.

I'm pretty sure I could work out some sort of placement so they got sun in the morning in part of the tub for their basking. I'm not so sure if I would need an actual pump/filter with this type of setup though. Since I would just be putting in about 12 in. of water, would I need a pump/filter? Or would it be just as easy to change out the water every few days (since the tub would have one of those drains on the bottom)?

And I'm also not sure about the best way to cover the tub-- configure some sort of mosquito screen? Or maybe something else? We have two 10kg dogs who are often chomping at the bit to get at the turtles when we have them out of the tank, so the turtle tub will definitely have to be enclosed. There are also lots of stray cats to consider.

Anyway, I welcome any thoughts on how to set something like this up!