Hi waterbear - thanks for your reply.

Yes, bottom line is, you're right, my cholorine was not high enough to keep pink slime away. And I knew that the preferred way to shock is to do as you suggest -- use liquid chlorine -- but I didn't have any and I was going out the door to work, so it was easier to hit Boost. That's not something I'd regularly want to do, though.

I did add more CYA -- not a lot -- so I'll see what it's like the next time I test for CYA or the next time I go to the nearby pool store.

My experience confirms what you said about the waterfall. When I'm running it, my pH rises about 0.1 per day. When I'm not running it, pH rises more slowly. I haven't detected, however, a similar bouncing effect by bringing my pH down to 7.2 after I add acid. pH seems to rise at the same rate irrespective of whether I bring it down to 7.6, 7.4 or 7.2 (I don't measure acid, so the lowering of pH tends to vary).

My grout issue isn't a water balance issue -- at least in the spot I've had trouble with. The problem existed after the pool was built in that one area of the swim-out. By the time I noticed it, the pool was full, and the too little grout wasn't a concern to me...except it seems to make it nice for pink slime to grow there. That said, I'm not familiar with CSI measurement, so if I'm subjecting my pool to the possibility of aggressive water as I try balancing my water, I'll need to do up my game a bit there. Based upon what you've said, it seems like upping my CH to maybe over 300 would be a good idea (Jandy recommends between 150-400, I think). Your thoughts on the optimum CH level for my pool?

Here's the one thing that niggles at me. I don't mind keeping FC higher than where I've kept it -- around 3.0 -- except that Jandy's SWCH says that I can cause damage to pool metals by maintaining FC higher than 3.0. I don't know if there were talking specifically about the metals as part of the SWCG, or if that's their position for general water balancing. Since all my Jandy equip is under warranty, I'm hesitant to maintain FC higher than 3.0. Thoughts on that matter?

Thanks