Green pool with clogged sand filter after 2 weeks out of town

[SunnyOptimism]

Actually, pools with a higher CYA usually can get by with less frequent dosing with bleach. Some people deliberately keep their CYA on the high side for this very reason.

Thanks, @Watermon.

I think it all depends on what is viewed as "high" and what set point you use for FC/CYA ratio. I try to follow the 7-11 formula for FC -> min FC level is 7% of CYA with daily target FC level of 11% of CYA.

Once you get much above 100ppm CYA, the 7-11 rule becomes much harder to maintain as my understanding is FC loss rate is not constant but proportional to FC concentration. So, at a higher FC level, you tend to lose FC at a faster rate than at a lower level. That was my point about more frequent additions.

Also, shocking your pool starts to become impractical at CYA levels above 150ppm as the amount of FC needed is quite high. I wouldn't go so far as to say you'll damage anything, but it will be a significant amount of chlorine to add and maintain. At some point, you reach a breakpoint where the cost of all the bleach you'd have to add (and time spent trying to maintain it and measure it) is probably as costly as just dumping half the water and starting with a lower overall CYA.

I'm not arguing against your point as I maintained my pool for quite sometime with my CYA at 90-100ppm, but I have the luxury of an SWCG and don't have to do any jug dumping.