I have to say I kinda laughed when I read your initial post, not at you, but at me. I finally got around to opening my pool this last weekend. Almost two months later than I usually open it. Needless to say, it was greener than green. No panic though, I already knew this process worked, so I did an initial CYA test on Friday and confirmed it was 0, or near 0. Checked the calculator and it said 1 gallon-ish of 10% chlorine would put me around 15ppm, so I just dumped in a gallon, a couple hours later I dumped in a gallon, and a couple hours later I dumped in a gallon, and so forth. The next morning I finally did a FC check. 50PPM! Ooops. 9 hours later, it was at 2ppm (Sun plus no CYA). Sunday my brush head fell off the stick while I was brushing the pool, couldn't see it. Got in the pool Monday and walked around for 15 minutes, still couldn't find it. Came home on Tuesday and I could see the bottom, but couldn't see the brush. Yesterday I found the brush and got it out! Today I came home and vacuumed the floor, had to backwash the filter 5 times while doing this. My pump has been on High for 168 hours, I've backwashed the filter 9 times this week, and I've been through 24 gallons of chlorine.
Basically, I'm getting lazier the older I get. It's completely my fault the pool was green to begin with. My new peristaltic pump showed up today also, so that got installed without haste! Now something mechanical can add the chlorine instead of me. Just gotta get it dialed in right.
So... Ya, I was laughing because I hit 50ppm! I also knew I should've been taking readings before adding the chlorine, so again it's just my laziness. It might also be the fact that we're waiting for our pool to collapse to put in an inground pool. It's really really old.
BUT
The pool will be ready this weekend! It's clear now, but not sparkly. It must be sparkly! It'll be sparkly by Saturday morning. I finally flipped the pump to low today, it seems to polish the water when it's running slow.