The best part about that DIY above-tank filter is if you use hydroton for your bio media, you can grow plants in it too :D. I have a peace lily in mine, but pothos and lucky bamboo are very popular as well. Something like this.
You can see lots of other examples on google...
I'm using the Tetra Whisper 40i in-tank filter. Once they're bigger and I move them into the larger tank with a higher water level, I'll add in a DIY overflow mechanical/biological filter as well.
After almost a year of trying to decide between the different muds and musks and going to two reptile shows fully intending to purchase one but no sellers had any, I ordered two three-striped mud turtle hatchlings from Robert and Trish.
They got here Thursday morning and after letting the rest...