Translate to:

Contrary to some misinformation that has lately been floating around, high cyanuric acid (stabilizer) levels do not cause gray discoloration, or white spotting (“spot etching” as some incorrectly call it) in plaster swimming pools, no matter what.  And there are several studies that have documented that.

The NPC/NPIRC Cal Poly Phase 4 study (2006-2007) showed that 250 ppm of cyanuric acid (CyA) didn’t cause gray discolorations or white spotting. In fact, in comparison to pools with zero, 50 ppm, and 100 ppm of CyA, the plaster pools with 250 ppm CyA looked the best overall after ten months.

A study by onBalance included placing a quality plaster coupon into (balanced LSI) water with 150 ppm of CyA, and an identical coupon into aggressive water (low TA) with 300 ppm of CyA. They were left there for one year. The picture below shows that the coupon submerged in 150 ppm CyA remained uniformly white and smooth (non-etched), and although it is hard to see, the coupon submerged in 300 ppm CyA had slight uniform etching and some exposed aggregate showing at surface. Note that neither of the plaster coupons resulted in gray mottling or white spotting.

The Dow Whitney study (University of Florida, 1990) concluded that Cyanuric acid alone was not a cause of leaching even at 500 ppm.

Even the 2004-2005 Arch Study provided further evidence that high CyA levels don’t cause gray discoloring or white spotting of pool plaster. Their study did show uniform etching (degradation) of the plaster coupons due to the water being aggressive, but not from high CyA only. It appears that the alkalinity had remained on the low side and was not adjusted upward to balance the water (per the LSI) when higher CyA levels (250 ppm) were maintained.

Why write about this high CyA issue?  Because there is one pool plasterer (and NPC member) that teaches at pool trade shows and at service tech’s chapter meetings that high CyA levels (above 50 ppm) causes gray discoloration and white spotting (spot etching). What studies does he cite as supporting his opinion? The same NPC/NPIRC and Arch studies mentioned above, which in reality, don’t support his claim at all, and in fact prove just the opposite.  

Views: 549

Comment

You need to be a member of Pool Genius Network to add comments!

Join Pool Genius Network

Comment by John on September 30, 2014 at 6:15am

How about some of the forced action mixers? Generally thought of as better mixers for tanking/ rendering slurries and often with plastic mixing tanks

http://collomix.de/au-forcedmixer.html

Comment by Norman Tyree on September 8, 2014 at 9:43am

Many problems are caused by the water used in the mix. yes even the Mixer made from steel it dosen`t help.

Rex you will never change the mind set of the plasters in a industry but it is still worth while trying.

Sign in

E-mail

Password
 or Sign Up
By signing in, you agree to the amended Terms of Service and Privacy Policy.
Forgotten your password?

Events

Latest Activity

Timothy M Kersting is now a member of Pool Genius Network
yesterday
John McGehee joined Brian Galella's group
yesterday
John McGehee joined Richard A. Falk's group
Thumbnail

Water Chemistry

This group is for in-depth discussion of pool and spa water chemistry issues at a more technical…See More
yesterday
Kim Skinner posted blog posts
Jan 17
Kim Skinner replied to John McGehee's discussion Issues with using rainwater for everything pool construction and maintenance related
"Using rain water for mixing with cementitious materials is fine.  I don't see significant…"
Jan 17
Kim Skinner's blog post was featured

The LSI is Reliable

Using the Langelier Saturation Index as a guide for maintaining proper pool water balance and to…See More
Jan 16
Jackie gingras is now a member of Pool Genius Network
Jan 15
Profile IconShaunta Clint and Marquise Pools, LLC joined Pool Genius Network
Jan 10

© 2019   Created by PGN Admin.   Powered by Pool Genius Network

Badges  |  Report an Issue  |  Terms of Service

Offline

Live Video