Trying to get chemical balance right in new pool

[jansenk511]

Hi,

I put up a new Intex Ultra Frame 16' pool in lat May/early June. I had researched using this site and had the Taylor test kit ready to go. Upon taking initial measurements on June 8th, I had a 7.1 pH, 40 ppm Alkalinity, 40 ppm Calcium, and 2 ppm Chlorine. That was the date I added CYA as well. The last test I did prior to coming back from a vacation was on 7/5 and I had a 7.2 pH, 110 Alkalinity, 90 Calcium, 6 ppm chlorine and 55 ppm CYA. When I tested this Sunday, 7/14, my measurements changed drastically with pH bottomed out and Chlorine at 0. I added some chemicals and as of tonight I'm at this measurement:

Chlorine: .5 ppm
pH: 7.4
Alkalinity: 160 ppm
Calcium: 120 ppm

I haven't retested CYA because I'm nearly out of the ability to test it, but I can if necessary. I was under the impression it shouldn't change much without a change in pool water of some kind. The SWG I'm using is 3 years old and an Intex brand but hasn't caused any problems in the past (although I wasn't testing this thoroughly with the good kit). Any advice? Thanks!

 

[Richard320]

pH shouldn't bottom out with a SWG. Off the scale high, yes. What was the reading and what did you add?

As an aside, whether it;s just a lot of sun, hot weather, stuff blowing in, SWG dying, or an impending algae bloom, you need to raise FC now. Add bleach - don't wait for the SWG to catch up. It might have died.

CYA reagent is cheap. Knowing your levels so you can adjust things properly is worth the small expense to buy refills.

You didn't, by chance, add any powdered "shock" and float a few pucks in the pool while you were gone, did you? And nobody "helped" you by doing it without mentioning it first, did they? Because a load of dichlor or trichlor WILL lower pH, and raise CYA to boot.

 

[jansenk511]

About how much bleach would I need to add to a 5000 gallon pool? How soon is it safe to swim in after adding the bleach?

The pH looked close to the 6.6 range when I tested it on Sunday. Not sure why it was so low, but when I added ph increaser that night and retested today it came back up to 7.4. I thought it was strange that the alkalinity has spiked so high, but tomorrow I will also test the CYA.

 

[duraleigh]

Poolcalculator.com will help you calc how much bleach you need. You can swim in the pool anytime provided your FC values do not exceed shock value.