Salt Water Generator / Intex Pool Question/advice

[Indywar]

Hi Aylad,

My CYA reading (dot test) was ~ 48ppm, pH=7.2, chlorine after 3 hrs of running SWCG (10:00 PM) was between 1-2 ppm, total alkalinity~200ppm.

Honestly, I never measured CYA, or anything other than pH with the other chlorinator the last several years. It was that dependable. Once I got the pH in range, & added the correct amount of NaCL at the beginning of the season I didn't add anything else all year: no stabilizer, maybe minor pH adjustments one or twice per season=crystal clear water with appropriate chlorine conc..
After pool season I drain the pool and store it.

As far as CYA earlier this year (based on the local pool shop....after reading your article on this forum I'm not sure what they are worth) 6/8/2012 CYA=10 ppm, 6/18/2012 = 25 ppm.

I tested the water right in front of the jet, where the chlorine conc. should be the highest and it was ~ 2 ppm.

I can check in the AM to determine chlorine loss, however there is an extra variable: the SWCG runs in the evening, so the chlorine should increase from now to the morning. If something was scavenging the Cl2, then the extra Cl2 produced by the SWCG could mask that effect. Anyways, I'll try to measure it tomorrow AM.

Thanks for the feedback. Unless you have other advice I will probable shock the pool tomorrow. How long should the kids wait after shocking before swimming?

Thanks,
Rob

[aylad]

There's really no reason to check for chlorine loss if your SWCG is running through the night--the whole point is to determine if something is consuming your chlorine, or if it's not being generated--and if it's running overnight, then any difference in the two readings is pretty much meaningless. If you need to shock the pool, you need to shock it and hold it there until you're not losing chlorine overnight. Could be one night, could be more, it just depends.

The kids should wait until you're finished shocking (no longer losing chlorine to anything other than sunlight) and until the chlorine levels have come down to an adequate level in your pool, which for a CYA of 48 should be at least 3 ppm before swimming. If you have something in the water that is creating a chlorine demand, then there's no chlorine left over to kill the viruses and bacteria that we're trying to protect the swimmers from!

[Indywar]

Checked Chlorine & pH at 7:30 AM: chlorine=1 ppm, pH 7.2