CYA question.


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I've heard on numerous occasions that CYA can lead to staining. Is this true? If so, why can it lead to staining?
It typically is only seen on fresh plaster when granular CYA is dumped into a pool and allowed to sit on the plaster surface without mixing. If you follow the methods we teach for adding CYA to a pool (the sock method) than it is a non-issue.


Active member
Feb 14, 2016
McKinney. TX
I have a Wet-Edge Technologies, Lunar Quartz finish in my pool.Basically it's colored plaster with some silica in it that produces pretty colors when the sun strikes it...and is harder, more durable than a typical white plaster finish. Mine is Bermuda Blue. At any rate, within a year of pool startup, I was getting white splotches on the stairs and pool bottom. At the time I was using a chlorine tab feeder and was testing the water about every two weeks at the pool company store....and following their suggestions as to what chems to add to the pool. My analyses always showed a CYA of 100+ and "adjusted" TA's of around 60. I was adding many pounds of their alkalinity + stuff on a regular basis and getting nowhere. After much debate and letters to both the pool company and Wet Edge, they both had their "plaster experts" render opinions based on my water tests.

Their analyses concluded that the combo of high CYA and low TA creates "aggressive" water that pulls calcium out of the finish and into the water. CH did rise over time. They concluded the resultant "staining" was the calcium being pulled out of the plaster. So, post draining/refilling a bit more than half the pool water, doing a light acid wash, and switching to an SWG system, I now have no further problems. I am also doing my own testing (Taylor K-2006), using TFP Pool Math, and spending a lot less on chemicals.

My final question to them was, had I just settled for the white plaster pool (white on white), would I have ever noticed the "staining." No response to date.....