I am literally at my witts end here and hoping someone here has some advice. I use 8.25% bleach, CYA is at 30. Been seeing brown spots in my pool for a few months now, I sweep it away and it disappears until the next day or two. During this time the chemical levels were all good--CYA 30, FC 2-4, CC 0, PH 7.5, Alkalinity 90. From what I read I determined the the brown spots to be mustard algae. The brown stuff was not gritty like dirt or sand, it was not pollen, if I touched it it would quickly disappear. It's normally found in the shallow end in different areas. I started SLAMing my pool Friday evening keeping FC levels at around 13 to 14. Pool finally passed the OCLT test yesterday on Sunday morning. I then raised to Mustard shock level of 19. A few hours later I checked and it dropped to 15 FC so I added more bleach and kept it at around 19 the remainder of the day. Today (Monday) I went and looked at pool and saw the little brown spots starting up in my pool once again. I don't understand, my pool is still at high levels and it's back already!! I have spent tons of money on this weekends SLAMing alone, and feel it was all for nothing. Any suggestions?? Thank you in advance.
vinyl in-ground pool
PH was normal at 7.5 but now high after all the SLAMing
pool is in full sun, temps stay in the 90's everyday usually all summer long.