CYA Reading after using R-7065 50ppm sample

[cpjolicoeur]

I ordered a bottle of the R-7065 CYA samples that is supposed to be pool water at 50ppm CYA level. I wanted to verify how close (good or bad) to accurate my previous CYA readings had been because I don't feel they have been very accurate based on the FC readings I get back.

When I used this solution in a CYA test, I personally tested this R-7065 to a reading of 30, not 50. I then tested my actual pool water and got a reading of 60.

How should I interpret these results? Should I use the ratio and assume that since my reading of 30ppm on what is a "known" 50ppm sample is a ratio of 3/5, that my actual pool water reading of 60 using the same ratio means my CYA is actually 100??

Or am I doing my baseline testing wrong. Should I use the known 50ppm solution and put into the black dot tube enough solution until it hits the 50 line, take a look at what the block dot looks like to my eye, and then try to hit that same block dot visibility when testing my actual water, instead of trying to wait till the black dot disappears?

 

[Griswald]

The second. See what a known 1uantity looks like and try to duplicate that result.

 

[cpjolicoeur]

For reference, here are some photos.

Here is the R-7065 baseline in the tube at the 50 line:


As you can tell, you can easily still see the black dot.

Here is my pool water at the 80 line:


I think this is the closes I could tell.

For reference, here is my pool at the 100 line:


Is there a better/more precise CYA test. For something that is so important and vital to knowing how high your FC needs to be for shock level, it's frustrating that this test is one of the most subjective to calculate, leaving it easy to be way off on your CYA value.

 

[AimeeH]

One of the most important factors in doing the CYA test is the lighting. You want to do this test in full sun with your back to the sun. Experiments have shown this makes a considerable difference. It might help to look away from the center of the vial, add enough to get to the next mark and then look at vial. Repeat until you don't see dot.

Your photos are not in direct sunlight.

 

[taylortechnologies]

We appreciate your comments regarding the R-7065 CYA Standard and the results you obtained. Standard solutions are designed to read a specific value. In your case, the R-7065 is designed to read 50 ppm CYA. Because the CYA test, a turbidimetric test, is in itself a subjective test, you can get slight variations on when the black dot just disappears. Consistency and carefully following the directions are the keys. There are colorimeter tests that take the human-factor out of finding the results.

 

[cpjolicoeur]

We appreciate your comments regarding the R-7065 CYA Standard and the results you obtained. Standard solutions are designed to read a specific value. In your case, the R-7065 is designed to read 50 ppm CYA. Because the CYA test, a turbidimetric test, is in itself a subjective test, you can get slight variations on when the black dot just disappears. Consistency and carefully following the directions are the keys. There are colorimeter tests that take the human-factor out of finding the results.

Do you have suggestions of the alternate tests that will remove human judgement from potentially skewing the results? Would like to check into them.

 

[JoyfulNoise]

One of the most important factors in doing the CYA test is the lighting. You want to do this test in full sun with your back to the sun. Experiments have shown this makes a considerable difference. It might help to look away from the center of the vial, add enough to get to the next mark and then look at vial. Repeat until you don't see dot.

Your photos are not in direct sunlight.

+1

As Aimee has stated, lighting is key. I have performed this test dozens of times over the years and I can say, unequivocally, that it never works properly with standard indoor lighting (perhaps a simulated sunlight light-table might work, but I'm not paying $200 for something I can get for free outside my back door). The test must be performed outdoors in bright, indirect sunlight and the tube walls must not be occluded by fingers. It seems counterintuitive that bright light will occlude the dot, but it does so through a process of light scattering making the turbidity appear stronger due to how the human eye works (low light vision is handled differently than bright light vision).

Redo the test outdoors by filling the vial to the 50ppm mark and then finding the outdoor lighting condition that produces the best possible reading. Do not intently stare at the solution, look away from time to time to de-focus your eyes a bit and always look directly and vertically into the tube, do not stare at it off-axis.

 

[taylortechnologies]

Do you have suggestions of the alternate tests that will remove human judgement from potentially skewing the results? Would like to check into them.

We offer the M-2000 Colorimeter which can be found here - http://www.taylortechnologies.com/products_kitinfo.asp?&MarketID=-1&KitID=2599 however, it may not be cost effective. The CYA Reagent Pack can be purchased with this to take the human error out of the CYA test. If you’re looking for something more affordable, a local pool/spa store that uses colorimetric or photometric analyses for CYA and other parameters would be your best bet.

 

[wjr75]

Wow that bad boy will set you back. I did liquid chromatography analysis in my research days in which the equipment back then was at least 10 to 20 times that. That would by all means beat any other method.

 

[jblizzle]

We appreciate your comments regarding the R-7065 CYA Standard and the results you obtained. Standard solutions are designed to read a specific value. In your case, the R-7065 is designed to read 50 ppm CYA. Because the CYA test, a turbidimetric test, is in itself a subjective test, you can get slight variations on when the black dot just disappears. Consistency and carefully following the directions are the keys. There are colorimeter tests that take the human-factor out of finding the results.

And yet almost consistently most members trying the standard are getting a 30-40ppm reading using your large view tube ...

 

[pooldv]

Agreed, i have tested with the 7065 standard on several different occasions and consistently read 40 ppm using both the 9056 comparator block and the 9193 tube. Using these reference photos as a guide, https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36

 

[aussieta]

and the sample should be held at waist level
your photo is much closer

 

[needsajet]

The only tip I haven't seen in this thread is to hold the viewing tube by the upper rim. Light has to get in to light up the suspended particles. But not so much to light up the dot, hence "back to the sun, tube in bright light, but not directly lit from above."

 

[domct203]

Agreed, i have tested with the 7065 standard on several different occasions and consistently read 40 ppm using both the 9056 comparator block and the 9193 tube. Using these reference photos as a guide, https://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=36

+1.

The only tip I haven't seen in this thread is to hold the viewing tube by the upper rim. Light has to get in to light up the suspended particles. But not so much to light up the dot, hence "back to the sun, tube in bright light, but not directly lit from above."

This is how I get my 50ppm standard to read 50ppm, I actually turn just a bit into the sunlight the illuminate the tube and can get the sample to read 50ppm. This seems strange as all the instructions and recommendations show to hold the tube in your shadow. When I do that, I consistently get 40-ish ppm.

Dom

 

[taylortechnologies]

And yet almost consistently most members trying the standard are getting a 30-40ppm reading using your large view tube ...

When you see anything that concerns you with a Taylor test, like getting a lower CYA level than expected, please call our help desk (800-TEST KIT) to discuss your findings with a qualified representative. Many factors go into getting correct test results (sample size, testing technique, reagent freshness, equipment used, …), and the deviations from best practices can add up to leading you to incorrect results. We are here to help.

 

[bkfamily1]

One of the most important factors in doing the CYA test is the lighting. You want to do this test in full sun with your back to the sun. Experiments have shown this makes a considerable difference. It might help to look away from the center of the vial, add enough to get to the next mark and then look at vial. Repeat until you don't see dot.

Your photos are not in direct sunlight.

+1

I have had times that I thought my CYA dropped 10 with no explanation - then I realized it was an overcast day - I wait a day or two for a nice sunny day, test again, and voila - right back where it was

 

[cpjolicoeur]

and the sample should be held at waist level
your photo is much closer

Photo was actually taken from eye level with tube on the counter, which is waist level.

I have to admit, I can't get this to work right.

I took the R-7065 50ppm sample and tried again today. Tried all kinds of lighting conditions. Sunlight at my back, at the side, at the front. Tried inside again. Tried various shadows and dark rooms. I can't get the 50ppm R-7065 solution in the tube at the 50 line to make the dot not visible.

Maybe if I get in a very dark room and look at it while it is on the floor I can not see it, but I can't image this is how the test is intended to operate.

I can't find a way in the naturally sunlight outdoors (with sun behind, on the side or in front) to make the 50 line work with the R-7065 solution and not still clearly see the black dot.

 

[TechnoGeek]

Me too.
AquaChek Test strips show my CYA is 40. With the TF-100 test I can completely fill the tube and it is still very visible in all light conditions.
the test 50 ppm solution tests almost the same.
My Sample Bottle for the solution actually measures to be 38ml to the top section of the large portion (below the neck of the bottle) by using a good quality syringe.
the bottom of the label is at 17ml and the top of the label is 33ml.
I will try my test again in the sunlight using exact 15ml portions of pool water and solution.
I hope my issue is relying on a incorrect sample bottle.

 

[needsajet]

I just want to say thanks and welcome to taylortechnologies

This is an important test to us, perhaps the most important, and it's wonderful that you're chipping in and helping us with it

 

[jblizzle]

I guess everyone should call the number that Taylor provided above about the cya test, because apparently none of us know how to use the standard correctly.

Report back the results and recommendations of the qualified representative help.