CYA and water temp

mrm1682 · May 3, 2023

Does CYA level matter more with warmer waters compared to cold?

Backstory and why I’m raising this question. I opened about 2 weeks ago when outside temp was 60-70. Since then we’ve had lousy weather, colder and a lot of rain. I’ve left the heater off and water temp has been around 58. My CYA at opening was 40 and I didn’t add any. FC has been steady around 4 and water is clear. My thought is just keep FC around this level and once we start getting warmer temps and pool gets some use get CYA up into range and then adjust SWG to keep FC in range.

Texas Splash · May 3, 2023

The R-0013 can be influenced by cold water. I would recommend grabbing your water sample and letting it sit indoors for an hour or so before actually doing the test.

mrm1682 · May 3, 2023

That’s what I was thinking of doing but does it even matter if algae doesn’t grow much below 60deg? I’m probably overthinking it.

Texas Splash · May 3, 2023

I would take advantage of the chilly water to ensure the pool is algae free. Do an Overnight Chlorine Loss Test first. If you fail, go right into a SLAM and it should go well in the cooler water. If you pass the OCLT, then you can slowly increase the CYA to meet your needs.

mgtfp · May 3, 2023

"Lousy weather and a lot of rain" implies not much sun (UV), which is what CYA protects from. The colder season comes with less UV and you'll get away with less CYA than in summerm

mrm1682 · May 3, 2023

Texas Splash said:
I would take advantage of the chilly water to ensure the pool is algae free. Do an Overnight Chlorine Loss Test first. If you fail, go right into a SLAM and it should go well in the cooler water. If you pass the OCLT, then you can slowly increase the CYA to meet your needs.

Good idea. I figured no algae since it looks clear and my FC has been fairly steady. But I shouldn’t just assume that.

an1vrsy · May 3, 2023

Another CYA testing method is to take your pool water sample, fill to the first line in the CYA test bottle with the sample pool water. Cap it then put it in your pocket. Perform all of the other tests, FC, pH and TA. After completing those tests, the CYA sample in your pocket has warmed up to room temp, add the CYA reagent to the top line, cap, mix and perform the test.