CYA problem


Well-known member
Jul 6, 2008
Pflugerville, Texas
I had to hire a pool service for about a year due to job travel. They used triclor pucks in a floater. I recently quit my job and fired the pool service when the guy said he'd have to drain my pool due to the CYA getting up to 100. It was time to get back to doing it myself (BBB method).
I double-checked the readings, and it was actually 100. It was as clear as a dew drop without any algae. We use a polyquat algaecide. (I have a Nautilus 48 DE filter and backwash every two weeks.) FC was about 2.0, but of course ineffective due to the CYA load.
I was not going to buy the snake-oil chemical treatment, so drained the pool as much as possible. The pump quit pulling with about a foot of water left over the drain, which was pretty good considering the challenge of pushing the water up a shallow slope for 100'. I was at least 80% drained.
I refilled and to my horror, the CYA is 80! I had it checked at the pool store and repeated the test. I'm using the TF100 kit.

The pool is a ~15K gallon in-ground lined with Wet-Edge Tech Prism Matrix two years old, if that could have anything to do with it??? All I can say is $%^$#!!!
I'm really reluctant to drain it again with my pump. If I have to drain it AGAIN I'd hire a pool company to drain it completely dry.
Is that what I am faced with? Not to mention a heck of a water bill.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

Not sure of your water rate, but here in Bedford I can fill my 17K pool for $50 bucks. If you tell the city they don't charge the associated sewer fee..

100 is the max the CYA test can see, so it could easily have been much higher than 100 ppm.

I never recommend using the pool pump to drain a pool. I suggest you buy or rent a submersible pump. Or your can just stick a garden hose in and run the other end down hill.. a little suction and you can siphon the water out. Takes longer but it is free..

Thanks for posting,

Jim R.


Sep 13, 2016
Tucson, AZ
My experience is that you have to be very careful with CYA measurements. The test kit that the pool store uses (and that I use now) only measures up to ~100ppm; anything over that still gets reported as 100ppm. I was in the same situation last year; the pool store said my CYA was 100 but I was completely chlorine locked so I ended up buying a Taylor kit, doing a 1-3 dilution of the pool water and, lo and behold, the CYA tested 80, meaning the original concentration was 320!
I rented a pump from Home Depot, drained and refilled the pool, and now only add CYA to 40ppm, then BBB all the way.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
pikeman, the math on CYA drains is quite simple. If you drain 50 % of your pool, the CYA reduces by 50%.

If you drain 50% of your remaining water, your CYA will come down to 40 ppm. easy peasy.

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