I've just moved into a new home and am glad to have found this site.
I have read through the Pool School section and feel I'm doing well with the chemistry of my pool. Chlorine and PH levels are looking good and the water has been crystal clear since I've cleaned the cartridge filters. (It didn't look as though they had been cleaned in a long time. Pressure was 20psi before and 7 after cleaning.)
Can somone please tell me what they think the valve does in the photo I'm attaching? Obviously the current setting goes to the filter. Is the other setting a drain to the sewer system? The pool has 1 skimmer and 3 jets and 2 bottom drains, but it doesn't seem to ever have any suction from the bottom. There is also a "hole" half way between the shallow and deep end about 12" bellow the water line that doesn't seem to do anything. The previous owner connected the Zodiac MX-8 to the skimmer port.
I am also seeing brown stains on the plaster that aren't affected by chlorine pucks left on them. The pool was replastered about a year ago. I was thinking about trying a Purity Pools "Underwater Acid Wash" kit to try and remove them. Has anyone had luck with this?
Thanks a bunch