When I first moved in, I was using a T100 filter that was installed in 1989 (we found the receipt). Worked great for a while then suddenly I was getting sand in the pool no matter what. I decided that it was old enough I wasn't going to try repairing it and put in the exact same T100. Problem solved, and like I said I never, and I mean NEVER, get any plume or sand into the pool. I've been so happy with the simplicity of my equipment, it almost takes the sting out of it all. I should post pictures of my plumbing and such again. It's bone stock simple. One skimmer, one main drain, 4 returns all at the shallow end blowing at the deep end (although during the replaster we put in standard returns and I modified the eyeballs so they circulate the water), then in the equipment room there is just the pump, SWG, and filter, with the plunger style diverter for filter/backwash. No valves, etc. I guess that's what you got in 1957.