My TA recently had to be increased from 70 to 90. Maybe there is high TA right at the swg cell or something?

As far as the white mold, what doesn't make sense is that I have never run biguinide in the pool and I don't think any of the previous owners did either. Maybe it is related to the solar fish I use to cut down on evaporative heat loss...I guess I'll just continue to vacuum the stuff out.