Lower CYA by adding water

Goong

In The Industry
May 7, 2020
2
Texas
Hi everyone,

I have owned a small new pool ( 10000-12000 gl ) for the first time for about two years. I tried to learn how to take care of it myself and it’s been ok so far except an algae issue last May. My problem now is the high CYA (about 150 tested by Taylor 2006 kit) and thanks to reading from TFP I now know it’s because I‘ve been using chlorine tablets. I‘ve read quite a few discussions about drain/refill or water exchange methods to lower CYA. What I don‘t understand is this: why can’t I just drop the garden hose to the bottom of the deep end and let the water run for a couple hours? The excess body of water near the sureface surely will go to the overflow and to the streets. Isn’t this an easy way (maybe less efficient considering the turbulence while adding water) to dilute the pool water and hence lower the CYA? Thanks.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,483
Laughlin, NV
Welcome to the forum!
It will work - IF - the fill water is much colder than the pool water. The pool water most likely has more calcium and salt in it than the fill water so you need a significant temperature difference in the waters (>10F) to keep a reasonable displacement.
I suggest you read ABC's of Pool Water Chemistry.
 

Goong

In The Industry
May 7, 2020
2
Texas
Welcome to the forum!
It will work - IF - the fill water is much colder than the pool water. The pool water most likely has more calcium and salt in it than the fill water so you need a significant temperature difference in the waters (>10F) to keep a reasonable displacement.
I suggest you read ABC's of Pool Water Chemistry.
Thank you so much for the advice, I guess I’ll have to measure the water temperatures before I add tap water.
Surely I’ll read the ABC’s.