CYA readings with PHOTOS....

[PoolBrews]

When reading CYA, I thought it might help if I took photos of the vial. In the photos below, the one on the left is using the 50ppm standard solution for TF TestKits. The photo on the right shows my pool reading that day (I had the vial filled to the 70 line).

As you can see, the 50ppm solution filled to the 50 line on the vial clearly still shows the black dot, while my pool water at 70 shows it almost gone... which leads me to believe I'm probably actually at 80, note 70.

Thoughts on using pics as a standard for more accurate readings? And thoughts as to why the 50 reading is still showing the dot pretty clearly?

CYA: 50 CYA: 70-80? (Pool)

 

[Texas Splash]

I've seen/heard of mixed results with the standard. Not really sure why. But the one on the left certainly looks like the dot is more obscured, so I would go with that number. The CYA 10% variance covers any small margin for error, so I think you're good. Here are some tips if you haven't already tried them:

CYA Testing:
Proper lighting is critical for the CYA test, so you want to test for CYA outside on a bright sunny day. Use the mixing bottle to gently mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, then gently mix again. Recommend standing outside with your back to the sun and the view tube in the shade of your body at waist level. Then, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. To help the eyes and prevent staring at the dot, some people find it better to pour & view in stages. Pour some solution into the viewing tube, look away, then look back again for the dot. Repeat as necessary until you feel the dot is gone. After the first CYA test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, gently shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate your own CYA reading. Finally, if you still doubt your own reading, have a friend do the test with you and compare results.

 

[ajw22]

Accuracy in CYA testing does not matter for our purposes as long as you measure on the high side. If your water is chemically CYA 50 and you chlorinate it as though it is CYA 80 then you just over chlorinate by a few PPM.

Call it what you want on the high side and move on.

 

[Bvacchiano]

My thoughts on CYA testing. Fill to 80 and see the dot, great! Fill to 50 and dot is gone. Cya is somewhere between 60-80. Keep FC at 6. Done.

 

[Holydoc]

I have had terrible trouble with the "Standard" solution. When I first got it, I was able to accept the 50 CYA reading. A week later and it was completely different with the 50 line clearly showing the black dot at the bottom. Now I just forget about the "Standard" and go until I no longer see the Dot clearly. I have taken a few test vials to the pool store to confirm my readings, but they are all over the place too. Just trust yourself and error on the high side.