My CYA slowly dropped to 60 with dilution and I noticed I needed to turn the output up a little on my SWG to maintain my FC. I did raise there CYA back to 75 (and may go a little more just to see what happens) and I was able to turn the output down. I know my chlorine use depends on weather, temp and pool load. Just curious if anyone else sees this correlation. This is my first year with a SWG and I love it! I don't miss all of the little bleach spots on my clothes.
SWG output and CYA
- Thread starter BCSB
- Start date
- May 3, 2014
- 58,499
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Absolutely. Dramatic effect here in the high UV desert. FC use jumps noticeably if the CYA drops below 70.
Thanks for the response. I raised it back to 75-80 and the difference was remarkable. I don't have the UV effect that you do but country living with lots of trees and critters puts my FC use at ~3ppm/day- more with a heavy swim load. What's the upper threshold for CYA other than the amount of chlorine I would need incase of a melt down? I was able to cut the run time on the SWG by half.
Mind quantifying what you mean by a remarkable difference? As in, are you able to share SWG % run numbers you had to run at 60CYA versus 80CYA? Was it like 80% down to 40% and still were able to maintain the same FC? Merely curious. Thanks.
- May 3, 2014
- 58,499
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Diminishing returns above 80. I would cap it there. Also keeps your target levels under 10 ppm. So your pH testing is accurate.
How does chlorine affect PH? Make it read higher or lower? Or does the chlorine bleach the red dye at higher amounts and that's why it is inaccurate?
Same with a meter? (If not the dye issue.)
Same with a meter? (If not the dye issue.)
It’s the phenol red affected by strong chlorine. Meters are not affected (but you have to keep them calibrated)
With the CYA at 60 I ran the SWG at 65% to maintain my FC level. At 75-80 now I'm at 35% and holding (or slightly gaining) the same FC. We're coming into a little cooler weather now and that will change it a little. 10 ppm now and I'll let that drop a little. I'm suspect of my PH reading but we'll see when it drops. I don't worry too much about it as my PH has always been fairly stable.