The CYA in my pool is something like 100.
By the way how do you measure CYA when looking for that little black dot to disappear at the bottom of the tube? I mean, is it when it's cloudy, or totally not able to be seen? Because I'd guess from person to person - one might be able to still see the dot, while another can't, and the difference of a couple drops can be ~10 on the CYA markings.. Anyway..
The high CYA is making keeping FC levels over 10 a real pain. And I'm having algae a bit and trying to SLAM the pool is insane trying to shock in the 30's - and I probably haven't got close to that, for some reason I'm scared to.
So the PoolMath calculator says I need to drain about 50% of the pool, about 7,000 gals. I have the Hayward c1200, so down at the bottom I can rig up a hose to drain from, but once I get below the skimmer air starts to get pulled in, as I can't completely shut off the valve - it's really hard to turn.
Is there a cheap sump pump at Home Depot or something someone can recommend? I'm overwhelmed by all the options online, and not familiar with pumps at all. What's a common method?