Not sure whether you're for real, or are a troll or spammer, so . . .

I'll answer your question;
What is a good option for a 6' deep pool with 6' diameter?
by saying, "I have no idea. You might want to look at the hydrotherapy industry. But that's nothing we know about."

And your 2nd question;
Do you think I can get by without filters?
by saying, "Only if you drain and refill with each use, and scrub or sanitize in between uses, like they do in hydrotherapy units."

And then, close the thread, with the note;
"Sorry, but this is not the right forum for questions like yours. I'm not sure what to suggest, except to look for advice from people providing hydrotherapy services.".

Good luck.