I'm not sure what brand it was (this was in 2001) but it was the type that hangs on the side of the tank, over the water, and has two filtration chambers, with the intake between them. The water was sucked up the tube between them, then split, half going into one chamber and half into the other. Once in the chamber, it went through a cartridge that had coarse filter cloth and carbon, and then exited the filter and fell back into the tank. It was made for a 50-gallon tank.
I've been searching online a bit but I can't find anything that looks like it as an example, but I can't find anything. It looks like power filters have become much more compact and more powerful since then
It was not powerful enough to suck up the water unless the tank was almost completely full, and with my turtle being a tiny hatchling, the water was not that full (this was before the advent of the turtle dock, so I was piling gravel at one end of the tank in order to give him a haulout.)
I went to an aquarium store to ask for help, and they made a graduating hose, attached to it the Askoll powerhead that I have mentioned elsewhere, and attached the other end of the hose to the intake on the powerfilter. That made it work, but it was, of course, super-noisy and very splashy. I could only run it with a towel draped over the tank to contain the splashes. So, I could not run it continuously- I tried running it for a few hours every night, with Al out of the tank (because the splashing scared him) and then ended up doing a LOT of water changes and etc.
If only I had known then what I know now! I really can't imagine what the guys at the aquarium store were thinking, either, except perhaps "easy mark." I eventually gave the filter away, to a brother in my fraternity, and bought my first Ekip.
I used to be a reptile expert. Now I'm just an old turtle lover.