Maybe just sematics but its not that the CYA makes chlorine less effective, its that chlorine loosely binds to the CYA molecule which protects the chlorine from UV degradation but reduces the amount of active HOCL in the water. The chlorine test can’t distinguish between the active HOCL and the “buffered” chlorine in the water. So all the HOCL in the water is just as effective, its just that theres less active HOCL when CYA is there.
Brand new pool owner, confused by readings
- Thread starter niilo
- Start date
cwswifty
Well-known member
- Sep 14, 2023
- 98
- Pool Size
- 26500
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Jandy Aquapure 1400
I believe I did read that you could use a good quality digital pH meter but I don't have any experience with them.
More info: PH - Further Reading
One other biggie - what is your water temperature? Here in the Mpls/St/Paul area I just barely hit 60 for a day, and now it's dropped a few degrees with the prolonged rain/cold front. I don't trust many of my readings when the water is cold.
Take your water sample, and bring it inside and allow it to warm to room temp. (or even put the closed sample bottle in some warmish water). Small amounts can just be tucked inside your shirt for a little while....
You may find with a not cold sample, your CYA tests lower.
I was a puck user for decades, but with lowering/refilling each winter, it never got near as high as you are showing. By the end of summer, it would be a bit too high, but not extreme. Then with the refill, it would be at the low end of recommendations. So a bit less likely your issue is due to carry over from the old owner - unless they deliberately added lots of CYA at the start of their season, and then never paid attention to how much more the pucks raised it.
What was bad with the pucks - I did not know about the increased CL needed as the CYA increased, so I was always fighting algae from July 4th on, even though I thought my CL was good.....
Take your water sample, and bring it inside and allow it to warm to room temp. (or even put the closed sample bottle in some warmish water). Small amounts can just be tucked inside your shirt for a little while....
You may find with a not cold sample, your CYA tests lower.
I was a puck user for decades, but with lowering/refilling each winter, it never got near as high as you are showing. By the end of summer, it would be a bit too high, but not extreme. Then with the refill, it would be at the low end of recommendations. So a bit less likely your issue is due to carry over from the old owner - unless they deliberately added lots of CYA at the start of their season, and then never paid attention to how much more the pucks raised it.
What was bad with the pucks - I did not know about the increased CL needed as the CYA increased, so I was always fighting algae from July 4th on, even though I thought my CL was good.....
You can do that. The downside is the meters require special calibration and storage/cleaning that was a big hassle when I got mine. Its way easier to just use the drops.
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@sande005 - thanks for that, it didn't occur to me that temperature could impact the readings - I'm in Michigan and the water is definitely cold 
I'll try to get some new ratings after letting it raise to room temp.
I'll try to get some new ratings after letting it raise to room temp.
- Jun 1, 2018
- 13,959
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Cya above 90ppm is quite unmanageable.
When you slip you’ll be draining so you can do the SLAM Process at a reasonable cya level anyway (30-60ppm) or it will cost a ton of $ in chlorine.
Water is cheaper than chlorine for most everyone.
Exchange some water if at all possible.
The no drain water exchange is the safest way to accomplish this.
www.troublefreepool.com
When you slip you’ll be draining so you can do the SLAM Process at a reasonable cya level anyway (30-60ppm) or it will cost a ton of $ in chlorine.
Water is cheaper than chlorine for most everyone.
Exchange some water if at all possible.
The no drain water exchange is the safest way to accomplish this.
Draining - Further Reading
www.troublefreepool.com