I started using these skimmers this year, I was wondering if anyone has experienced a slow rise in PH level with the skimmers. It seems like my PH slowly rises from 7.4 to 7.8 over a period of four days and TA seems to follow, CH stays the same, this didn't happen last year when I was using the original baskets and can't seem to find another source for the slow rise of the PH and TA. everything else is stable. Any thoughts?