pH drifts from 7.5 to 8.0 in less than a week. Do I go for a lower TA? This has been a constant issue. I keep waterfalls off 95% of the time. Wife turns them on when company is over. The 1.5hp single speed pump moves the water very well, almost aggressively if you get my meaning. You can see the water swirling all the time when it is on. I just want to be able to keep a constant pH of ~7.6 for a few weeks. Any more ideas?