a thought about CYA during a SLAM

[bkfamily1]

I wanted to share an observation from the SLAM I am doing.

When I started, my CYA (as tested by the pool store) was 65. As the SLAM has progressed, the CYA has dropped to 40 and now 30. I understand that has probably not really happened. Even though I have been filling to replace the water lost from frequent DE backflushing, I don't think it was enough to cause that change.

It occurred to me that when I started the water was very cloudy. In a typical clear bottled water bottle, the cloudiness was very apparent. And the CYA test depends on the cloudiness of the sample obscuring the black dot (by the way my pool staore does the exact same test). So my conclusion is that when the water is cloudy, as it often is when people start a SLAM, you can't trust the CYA reading which will likely test higher than actual.

 

[Texas Splash]

Might seem like a logical conclusion, but I would have to disagree. The CYA test isn't based on the cloudiness of the pool water itself, it is a chemical reaction between the water, the organic/inorganic particles remaining, and the reagent we mix in the missing bottle. That's what allows us to find the correct CYA. Others may have a more scientific answer, but that's my lingo. Pool stores notoriously get this test wrong either through improper training, doing the test in a hurry with 10 customers waiting, or because they are indoors using incandescent lighting.

 

[duraleigh]

It's a good thought but it doesn't work out. Unless your pool is so murky you can't see 3" or so, it will have no effect.

Simply take a sample of your pool water and put it in the view tube without adding any R-0013. 99% of you will get 0 CYA as a result. In other words, you will be able to see the black dot clearly.

For those who's pools are the consistency and color of chocolate cake batter uhh, do the same thing. Now, if you get a CYA of say 30 ppm, you can then add the R-0013 and get a result of maybe 90 ppm, meaning you have 60 ppm CYA

 

[Texas Splash]

Part of the validation about my comment is the pool store CYA test being different each time you went. That's next to impossible unless a significant amount of water was removed/replaced. Chances are if you took a water sample to 5 different pool stores, you would get 5 different results. That's exactly why we emphasize the TF-100 or Taylor K2006 kits so YOU can be sure the readings are good for yourself.

 

[bkfamily1]

You could be right Texas. I was just trying to figure out why it had dropped so fast in 3 days.

FYI, the pool store did the first test, but the other tests were done by the store and me (using the TF100) and our results matched.