I sounds like either what Watermom suggested, and it's just residual dirt resettling (I have a couple of spots in my pool where dirt reappears daily), or it's possible that your cartridge filter is being overdriven by your pump, and what you're vaccuming is just going through the filter and back into the pool. What size pump is on the pool? Also, if you'll list the other water test results that Watermom asked for, we can help you figure out how much acid you're going to need to drop your pH. Have you recently had an algae bloom?