Hey neighbor! I find myself adding CYA too. My pool has no auto drain so I know every time I'm pumping CYA out of the pool. Also, since it's a salt water pool, I have to adjust for that. Still, for some reason, the pool goes through more CYA than would be expected based on water exchange, splash out, and draining. I find myself adding CYA granules once a month. I only add salt a couple times a year. Nobody seems to have an explanation for it because the common thinking is that CYA isn't normally consumed. Nobody told that to my pool!
As a gardener, I've learned that "rules" I read written for anywhere else on the planet don't apply in South Florida... come to think of it, "rules" of the "road" and other niceities don't apply here either, maybe it's just a parallel universe.
When I first came here, after 7 years of using tons of pucks, I expected a high CYA. I was stunned when I had to add stabilizer. I have a sock in the skimmer and a sock in the tablet floater, aiming for around 30-40 for effort one.
I'm thinking with the summer sun/rain coming out, I might go back to pucks + liquid chlorine and test the CYA regularly, if it starts to creep up, stop the bucks and watch?
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Alex, I think you hit that one on the head - water exchange. If I recall correctly, FL has had a wet season already, and all of that water exchange is bound to lower CYA. There's nothing wrong with using those pucks for a short time, but in your case ... with CYA being at zero right now .... you can't afford to wait on the pucks to raise it. Use some stabilizer right away and shoot for at least 30 ppm. Do that now, and if you want to use a puck or two here & there it's okay, but remember to watch the CYA level and also that pucks are acidic. So pucks will drive-down your pH and TA as well.
In addition, watch your FC closely right now since without any CYA (at the moment) your FC will disappear very fast to the sun. Now if you are starting to see algae now, let us know and/or start a SLAM right away (link below).
Hope that helps.
FYI: Did a mini-SLAM over the past few days, testing 1x-2x/day, adding bleach morning and night, and running the filter constantly. Looking clear after about 3 days (I didn't do that entire week+ process I did to go from green to clear). Going to clean filter again and do an overnight test.
But I'm leaning towards pucks as part of keeping pool from getting green.
Some years back, on my fathers suggestion, I used the Extended Control Algeacide that lasts for 3 months. If I remembered to do it every three months, I never got algae as long as I was "decent" on taking care of the pool. It's slightly more expensive than a pure BBB solution, but I'm considering it to reduce the risk that I get busy at work and neglect pool for a few days and the pool goes green.