I have a floating mini-chlorine tablet holder: https://www.amazon.com/dp/B07RTWDX5D?ref=ppx_pop_mob_ap_share
For filtration, I added a suction hose strainer tip that I found at Tractor Supply and I stick an Intex filter over it. The only thing is that you have to plug one end - either with a rubber plug or by gluing a piece of rubber/foam over one end. I’m still perfecting that part.
As far as water changes, I don’t do any. I keep the water filtered and chlorinated and use a simple pool water test kit.