OCLT and Rain

[reggiehammond]

My reasoning for saying don't increase CYA is you continually find yourself under minimum FC requirements. When you're under minimum, organics can take off. You may have algae and you don't know it. Increasing CYA just makes the FC less effective if you find yourself low, and makes the SLAM process more expensive.

Why are you struggling to maintain FC at CYA 40? That's not normal.

I'm just worried you don't quite have the TFP basics down. Your FC should NEVER be below minimum and you seem to not quite understand the
FC/CYA Levels. Not trying to be too sharp, just want to help you avoid any larger problems.

 

[mas985]

My experience has been that when I increase CYA but keep FC dosage the same (i.e. same SWG %), the FC/CYA ratio actually increases. These threads document the testing:

CYA Testing Update

I thought I would give those who are interested an update on some testing that I have been doing regarding CYA levels and chlorine. First a summary of the testing that I did in this thread. - Running my spa with the SWG at CYA levels from 45-80 ppm showed no change in chlorine production. -...

www.troublefreepool.com

CYA vs UV Chlorine Loss Test Update

Many years ago, I did a test of chlorine loss vs CYA level and published the results here: https://www.troublefreepool.com/threads/cya-testing-update.2984/ There were a few issues with the test that I wanted to resolve with some additional testing but never got around to doing it...until now...

www.troublefreepool.com

 

[Pharmacyman]

reggiehammond, the reason I was struggling to maintain FC was because I had a new SWCG installed and was having flow problems due to a clogged screen...which has since been resolved. My earlier post reported crystal clear water and CCs of zero.

I did OCLT again last night...this time properly with chlorine generator shut off.

Last night PH 7.7, salt 3400, FC 3, CC 0, CYA 50
This morning FC 3

 

[reggiehammond]

Ok - if I were you, I'd raise the FC to 8-10 and try to stay there. FC of 3 is low for CYA 50, but in range. I would just contend it's not wise to be on the low end, as one heavy bather day, a lot of junk blown into pool, etc and you're in algae land.

 

[SJPoe]

Ok - if I were you, I'd raise the FC to 8-10 and try to stay there. FC of 3 is low for CYA 50, but in range. I would just contend it's not wise to be on the low end, as one heavy bather day, a lot of junk blown into pool, etc and you're in algae land.

I agree. There simply is no good reason to 'ride the line'. Your filterscreen could clog again, and a day of low flow means suddenly you're below the line, and heading for a green pool.

Bring that baseline up - shoot for the middle if you like. Don't be afraid the pool is going to be all chlorine-y and smelly...it just wont. If your CYA and FC are balanced, you simply will not notice.

My pool today is probably about 10ppm / 80cya, although I haven't made it out there to run the tests.
If the SWG was off for 24 hours, and it dropped 4ppm, I'd be at about 6...still comfortably about my minimum.
My last guest swimmers commented on how nice it was to swim in a pool that didn't sting their eyes, and didn't smell like a pool

( Edit : i made it out - 9.0FC, 0CC - but its about 2 hours later than I usually measure, and its really sunny out, so I'm not going to sweat the 1ppm )