High FC and High pH

Deb04

LifeTime Supporter
Jul 12, 2008
650
Seacoast, NH
Pool Size
19000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I know I have seen this answered on this site many times before, but I can't find it. Please forgive me asking a question addressed in other threads.

My CC is usually zero. I hate it when it isn't. Yesterday the CC was < 0.5 and there was this yellow junk on the bottom of the deep end. When I brushed it, it made the water on the bottom of the deep end look like weak tea. The water also looked just the teeniest bit cloudy. It had been more than a couple of days since DH vacuumed (we have a deal, I deal with the chemicals and he does the vacuuming), so I didn't know if it was dirt or something growing. So, I decided to bring the chlorine up to shock levels and convinced DH to vacuum last night before the major heat wave hits today.

Pool passed the over-night test and there's nothing on the bottom of the pool today. Water looks clear.

Numbers as of now:
FC 17.5
CC< 0.5
PH at least 8 (as high as K2006 goes)
CYA 50 (I know it's low for SWG, working on it)

Yesterday the pH was 7.8. Last night I added enough dry acid that the pH should have been brought down to 7.5. (I've been slowly adding borax for the first time. I haven't added any since Sat). I know I've read that high chlorine can cause messed up pH readings, but I can't remember if it causes false high or false low results. If it causes false low, I think I'm in trouble, but I don't know what caused it.
 
I've been testing my pH with FC @ 11.5-12 at time of testing. It seems to be accurate. My pH was 7.2 for a long time, I made a fountain and it goes up about 0.2/day. (~12hrs run time) I shouldn't say for sure though, I've only been running it for one day. I used left over powder last night, but tonight I'm picking up some muriatic acid. Before the fountain my pH seemed to be steady at 7.2-7.3.
 
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