I posted a couple of questions in early June '15 re; CYA and iron control after I re-filled my AG pool with its new vinyl liner. Thanks to the great replies I received I've learned and observed some vital facts. I've been in the industry for way longer than I care to think about, yet have overlooked - out of ignorance and disbelief - the importance of CYA in the Tri-chlor tabs so many of us use. The past few years I've gone through way more chlorine and algaecide than was reasonable. This year, on a fresh water fill and after getting the iron from my well water handled, I tested daily and observed:
1) My pool was absolutely trouble free, crystal clear and algae free all summer.
2) I didn't add any algaecide after two weeks of removing the iron with no chlorine in the water.
3) I added enough "stabilizer" (CYA) to bring the initial CYA count to approx. 10ppm. (Tested for with my new test kit from TFP)
4) I went through 7 gallons of muriatic acid a little at a time in order to bring the TA from 410ppm (yes, you read that right) to the 120 ppm it is now.
5) I ran the pool all season with 3" Tri-chlor tabs in my online feeder. No muss, no fuss, simple and troublefree.
6) ALAS! Over the course of the past 2-1/2 months, the Tri-chlor pucks raised my CYA to 55ppm! From 10 in mid June to 55 on Aug. 31st! Gasp! OK, I'm a believer. My pool won't be trouble free for long using pucks!
7) I went to hand feeding liquid. But, what a pain. I see with great interest a forum on ORP controllers and auto-feeding liquid - just like I did when I ran commercial pools back in the '80s. Kool! Next year's project.
Thanks for a great website~! A closing pic of my remodeled pool -