CYA images

[Sotex]

These were all taken from the same distance and then cropped.

For such a subjective test, thought I’d post these images to see which CYA level the forum would assign.

 

[HermanTX]

Definitely less than 80. Not sure what 60 or 70 level mark would look like but I think it greater than 50. You could argue that it is 50 because it is barely visible, but I just glance at it and if I can see I add solution to the next level, if not, I stop. So I would pick 60 or 70 even though there is no picture. I go in 10 increments. If I can see it at 80 but not at 70 then it is 80. If i can see it at 70 but not at 60 then it is 70.

 

[Sotex]

Definitely less than 80. Not sure what 60 or 70 level mark would look like but I think it greater than 50. You could argue that it is 50 because it is barely visible, but I just glance at it and if I can see I add solution to the next level, if not, I stop. So I would pick 60 or 70 even though there is no picture. I go in 10 increments. If I can see it at 80 but not at 70 then it is 80. If i can see it at 70 but not at 60 then it is 70.

60 and 70 looked a lot like 80. I went with 40 initially. The subjectivity of this test is challenging.

 

[PoolNewb2020]

Personally I don't find this test all that difficult. Just don't stare at it trying to look for the dot, or try to be precise with the level the dot disappeared at.

I just add a little bit at a time and glance. Add more and glance again. Repeat until I don't immediately see the dot and I never check the level between reading. I add the solution while still looking down at the tube. This way I don't know how much I added. When i finally don't see the dot, I check the level and usually round up.

Some people fill to a specific level and then check, but IMO, this method adds more bias because, unless you don't know the previous CYA reading, you will be expecting the reading to be close to a certain level, hence increase the bias.

 

[Richard320]

That looks like it was taken indoors. I always do the CYA test on a sunny day, on the patio so it gets all kinds of light reflected up off the concrete besides the sunlight. And I only hold it at the very top, because the lower fingers block light. I checked myself using the CYA standard solution, and that's what it takes for me to be accurate.

 

[EJ39]

Probably a stupid question, but was is the procedure for using the 50ppm standard solution?

 

[Danforth]

I agree that the test is best interpreted in indirect sunlight. If I had to guess based on the photos provided, I’d just call it 80 CYA.

The standard solution is used in place of your pool water. Perform the test in the same way, but use the solution instead of your own pool water.

 

[EJ39]

I agree that the test is best interpreted in indirect sunlight. If I had to guess based on the photos provided, I’d just call it 80 CYA.

The standard solution is used in place of your pool water. Perform the test in the same way, but use the solution instead of your own pool water.

So the black dot should disappear at 50ppm correct using that solution?

 

[SouthVirginiaPool]

I picked the middle picture at 40 ppm

 

[Richard320]

So the black dot should disappear at 50ppm correct using that solution?

Yes. So you adjust your technique to read 50, then do just the same with pool water later. You'll figure out how to hold it, how far away from your eyes, how much light, everything.

 

[EJ39]

When I add the solution with the reagent the test is clear all the way to the top of the tube. What am I doing wrong?

 

[Richard320]

When I add the solution with the reagent the test is clear all the way to the top of the tube. What am I doing wrong?

Half R-0065, half R-0013. It should get cloudy. Then you pour it into the view tube.

 

[Sotex]

That looks like it was taken indoors. I always do the CYA test on a sunny day, on the patio so it gets all kinds of light reflected up off the concrete besides the sunlight. And I only hold it at the very top, because the lower fingers block light. I checked myself using the CYA standard solution, and that's what it takes for me to be accurate.

Retested using your advice and it’s closer to 40 than 50, but I’ll call it 50.

 

[EJ39]

Half R-0065, half R-0013. It should get cloudy. Then you pour it into the view tube.

That’s exactly what I did and it’s clear? When I use pool water I’m coming up with approximately 70

 

[Richard320]

That’s exactly what I did and it’s clear? When I use pool water I’m coming up with approximately 70

I'd say you have a bad batch somehow.

 

[Sotex]

That looks like it was taken indoors. I always do the CYA test on a sunny day, on the patio so it gets all kinds of light reflected up off the concrete besides the sunlight. And I only hold it at the very top, because the lower fingers block light. I checked myself using the CYA standard solution, and that's what it takes for me to be accurate.

I meant to say earlier - it was done outdoors but I came in to get my phone and took the pic indoors.