I guess my former -- and not missed -- pool guy must have continued to add stabilizer to the pool without bothering to check for CYA levels. Else how could it possible have gotten so high? Far as that goes, it appears that the cheesy little sight glass thing he was using to check the pool chemistry with was probably just about useless anyway. The fact that the rest of the numbers are off as far as they are is a pretty good indication of his incompetence, I'm thinking.
I just read through the SLAM process again. Yeah, it appears that, with my CYA level as high as it is, I'm gonna have to drain some of the water. It's starting to get pretty warm here in Houston. Daytime temps up in the 90s. So I guess I'll drain the pool at night. Maybe tonight, if I can find the fitting I need.
This pool's piping to and from the pump is extremely basic. There's a pipe coming into the pump from the skimmer box, a pipe from the pump to the filter, and a pipe from the filter to the pool. There is a fitting at the bottom of the cartridge filter's housing, slightly smaller than a garden hose end. I'm gonna go down to Home Depot and see if I can find an adapter that will get me from a garden hose end to that size fitting. Then I can just hook up the garden hose and drain the pool from the filter. Or maybe Leslie's Pools will have it? There's one not too far from my house. They're closed now, so if I go that route, it'll have to wait til tomorrow.
If I can't find an adapter, then I'm gonna have to get more creative. It'll involve cutting the PVC pipe running from the pump to the filter and inserting a two-way valve to which I can attach something that I can drain the pool with. Seems to me, it might not be a bad idea to install this sort of bypass valve anyway. Plus, the flow rate will be much higher than it will be through that small hole at the bottom of the filter.