My pool (see signature) is 6.5 years old and has never been drained. For most of its life, I've maintained chlorine levels using trichlor tabs in the skimmer and broadcast dichlor to shock. Recently, it's been harder to maintain adequate levels, and I've had problems keeping algae away. Exasperated, I looked around the Internet, found the Pool School, and read everything there. Now I think I understand the problem much better. I got a good testing kit, and found that CYA was (not surprisingly, given my previous method of chlorination) off the scale: the scale is logarithmic, and I estimate by extrapolation that it's around 160. Around the same time, a friend of mine in the pool business had his maintenance guy come by to check things out for me as well. He tested the phosphates and found them to be very high. He put in a bottle of phosphate remover, told me to run the filter overnight and clean it the next day, which resulted in lots of blue cloudy water coming out of the cartridges during cleaning. He didn't seem to understand what was wrong with high CYA, and said that many of the pools he services have high CYA without problems.
Last night, early evening, my test results were:
CH : 310
CYA: 160 (est.)
I was never told the volume of my pool, so after this last test, I added 2 gal of 10% bleach, ran the filter in the dark for several hours, and retested FC at 10.6 (CC still 0.2). From this, I calculated a pool volume of 22K gal. This morning, before the sun hit the pool, FC was 9.2 and CC was 0.
So, here are my questions:
1. It seems clear that I need to drain the pool, but it's too hot for that now (or so I've been told). City codes allow homeowners to drain their pools more frequently than the required three years if CYA is over 100 (or TDS is over 2500, or CH is over 450), but there don't seem to be any regulations about maximum CYA. Is the pool safe enough to swim in? If so, what's my best course of action to keep the pool in swimmable condition until the late fall/early winter? The Chlorine/CYA chart seems to require possibly dangerous levels of chlorine (on top of the already high CYA level) for sanitation.
2. Is the phosphates level something that I should regularly test for and correct, as the pool guy seemed to suggest? From what I've read here, it seems little more than a cash cow for the pool industry -- although what the service guy said about it being a problem made some sense.