CYA Sample Solution (50ppm) Photo

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mcolflesh

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Mar 8, 2017
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Coopersburg, PA
I have been trying "calibrate" my eyes to read the CYA test so I ordered the R-7065 Sample Solution from TF Test Kits. I went out this morning with my TF-100 and R-7065 to get a photo result of the CYA reading of 50. I added R-7065 to the bottom of the CYA testing bottle label and filled the rest of the testing bottle up to the top of the label with R-0013. I shook the test bottle with red cap for 30 seconds and let it sit for 2 minutes. I then shook it again briefly and set myself up with my back to the morning sun and the CYA view tube at waist height. See below for the photo taken from about the distance of my chin to the view tube at waist height to see the 50 reading on the view tube.

View attachment 62628

If this reading is 50ppm then I've been reading my CYA readings too low. The black dot didn't completely disappear for me on the test solution until about 40ppm. Thoughts? Is my testing method off? Do my eyes just need to "calibrate" to this way of seeing the black dot disappear?

A follow up question as well since my CYA result interpretations are likely off - during my SLAM, what should my Combined Chloramines be reading? I'm getting barely .5 for CC and I'm into day 3 of my SLAM, but I've been basing my FC goal off of a CYA of 40. I should probably be aiming for FC of 20 since I'm likely at least 50-60 for my CYA.
 
You have to assume the standard is correct. Lighting can affect the result quite a bit, unfortunately. When I test mine, I make sure to have all my fingers except for the thumb and forefinger holding the vial well away from the vial, not blocking any light to it. I also only test on sunny days when the sun is relatively high, but at my back. It's unfortunate that the test is subjective as much as it is and really is only accurate +/- 10 ppm.

Test the standard and your pool water under the same lighting conditions again. If results look similar, your CYA ppm is 40 ppm and base your SLAM on that number.

During a SLAM, you'll really only see CC above 0.5 early in the SLAM. Once most of the active algae is gone, CC levels won't be very high. Usually the order that the criteria are passed is the CC <0.5 ppm first then a close race between the OCLT and clarity.
 
Wait a second, I'm confused. Is the R-7065 supposed to be a sample of pool water with 50 ppm CYA so that you need to mix it 50/50 with 0013 and then test? OR is it already mixed and you just perform the test with it? If the latter is true, mixing it with more r-0013 would mess up the test.
 
The R-7065 is to be used as pool water, so you mix it with R-0013 in a 50:50 ratio and then calibrate your eyes to see what 50 ppm CYA looks like. I find it is important to mix and wait 30 seconds to let it mix together.
 
By calibrate your eyes, they mean: Fill the tube to 50 and look at the dot. What YOU see is 50. Some folks think that your picture above shows a barely visible dot, and other folks think that it's very easy to see.
So what you should do is use the 50ppm test solution to know what 50ppm looks like to you. Then duplicate the same lighting and tube position when you do the testing with your pool water.

Does that help at all???
 
pabeader said:
By calibrate your eyes, they mean: Fill the tube to 50 and look at the dot. What YOU see is 50. Some folks think that your picture above shows a barely visible dot, and other folks think that it's very easy to see.
So what you should do is use the 50ppm test solution to know what 50ppm looks like to you. Then duplicate the same lighting and tube position when you do the testing with your pool water.

Does that help at all???
Click to expand...

This is a great post. I'm starting to think that what pabeader has described above is the gold standard of CYA testing, and since the CYA level is integral to the TFP method of pool water management - should be done at least once per season.

Regards
 
I got a pint bottle of R-7065 standard last season to calibrate my readings. When I mixed up my first sample I was surprised there was no trace of the black dot or the white background at 50ppm. Nothing like your picture. I've retested several times along with new R-0013 this season with the same results.

I use my Seedstir for 30 seconds and then wait several minutes for the trapped air bubbles to dissipate.
 
Couldn't you just make this yourself? Fill a 5 gallon buck with water, add 4.3 oz of stabilizer until it dissolves. Use that as sample. You could probably scale it down even more, but seems fairly easy to recreate your own sample of water with CYA of 50. My guess is most already have that little of stabilizer laying around.
 
spinPHD said:
Couldn't you just make this yourself? Fill a 5 gallon buck with water, add 4.3 oz of stabilizer until it dissolves. Use that as sample. You could probably scale it down even more, but seems fairly easy to recreate your own sample of water with CYA of 50. My guess is most already have that little of stabilizer laying around.
Click to expand...

To get 50 ppm CYA in 5 gallons of water it would take 0.033 oz weight of stabilizer, which is probably just a few crumbs.
 

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CA92807,

When you say you use your speedstir for 30 seconds and then wait several minutes for the trapped air bubbles to dissipate - what is several minutes? Three to five? More? Also, do you use the CYA measuring bottle with the red cap to measure out your pool water and R-0013 or do you measure even amounts of each in a graduated cylinder?
 
I use 10 ml of water, 10 ml of reagent. Mix for 30 seconds and let it stand for at least 2 minutes. Then I transfer to the red cap bottle and fill the sample tube until the black dot is occluded. I note the value and repeat until I get a consistent reading. Then I repeat the test with my own pool water.
 
CA92807 said:
I use 10 ml of water, 10 ml of reagent. Mix for 30 seconds and let it stand for at least 2 minutes. Then I transfer to the red cap bottle and fill the sample tube until the black dot is occluded. I note the value and repeat until I get a consistent reading. Then I repeat the test with my own pool water.
Click to expand...
If you repeat with your pool water, what water are you using initially?
 
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