Hi everybody. My pool water has been crystal clear until today. Here's the situation. I bought a robot cleaner last year which didn't work when I got it and now it's quit again. I'll post that in another forum. None the less, the pool has been sitting with several small piles of dirt in the bottom which I periodically brush up to get it circulating around. As I said the water has been crystal, the best ever. However, tomorrow afternoon my wife has a freshman girls youth group coming to swim. So I got out the old PoolVac and got it to going. Before putting it in I backwashed the filter which I hadn't done in probably 3 or 4 weeks. For some strange reason when the Pool Vac is connected it sucks in air. I haven't been able to locate the air leak but its only when I throttle the bottom drain line to get the right dP for the PoolVac, which I can't get the 10" wg it needs due to too much air. That's why I bought the robot. Bummer. Again, that's for another forum. With the air entrained I get lots of air bubbles in the first return. The question is why did my water get hazy and it did it really fast. Was it the backwashing or tiny bubbles increasing PH which I don't see how that could happen that quickly. Could it have been something else? Here's my #s: FC 5.5, CC 0, PH 7.6-7.7, TA 90, CYA 45-50.