I just wanted to drop in and put in a plug for the TFPC method, in case there are any skeptics out there reading these forums wondering if they should try it.
Back in late June or early July of 2011, I'd done the routine bi-weekly shock our pool store recommended and a day later, the water looked a bit cloudy and I had FC readings off the charts that wouldn't come down. When the pool store recommended I shock again, the penny finally dropped and I realized these guys didn't know what they were talking about. I'd been on this site before and pulled it up again and read Pool School closely. Not having a good test kit, I took a sample to the pool store specifically to find out what my CYA level was. Their test, which the kid seemed unsure of, showed what I expected: a CYA reading off the chart. Naturally, they gave me a shopping list of stuff to buy, which I ignored. I went home and drained as much out of the pool as I dared, and refilled. The July 4th holiday was coming up, and that's kind of a big deal at our house.
The water started clearing and by the time of our July 4th bash was looking good. I continued to watch the chlorine level gradually drop, and when my TF100 kit arrived the first thing I did was a CYA test. I don't recall exactly what it was now, but it was around 150. And remember, this was AFTER draining about 25% of the pool volume and refilling. Over the rest of that summer, we did a few more partial drains and refills and watched the CYA continue to drop. Over the 2012 and 2013 swim seasons, we stuck to the TFPC method and had zero problems. Last summer I never even had to SLAM the pool. Not once.
This summer, we started the season with a CYA of around 35, which is right where I want it to be. Knowing we'd be vacationing for a week in August, I've been deliberately letting the CYA drop so I can float a bunch of pucks while we're gone, and a few days ago it was around 25. That seems to be the level at which chlorine consumption becomes excessive. I skipped a day and ended up having to SLAM for a day, which set things right once again. I'm floating a couple of di-chlor pucks right now to nudge CYA back up a bit, and I learned something about the pucks.
These pucks are leftover from 2011, when we stopped using the pool store method. The first day the pucks were floating they had zero effect on the chlorine level, so I tossed in more 12.5% bleach. Today's test showed nearly no loss in chlorine, so my theory is that pucks age from the outside in. There was little to no active chlorine remaining on the outside of the puck, but as they dissolved, the inner regions of the puck still had active chlorine which is now being released into the water. Sort of makes sense, I guess.
Anyway, the takeaway from this somewhat rambling post is that TFPC works. Don't question it, just do it! I'm forever grateful to this site and its many contributors because it's made life a whole lot easier, and my pool more enjoyable.
I'll add as a PS: Borates, shmorates! If my water sparkled any more we'd all go blind!