CYA measurement

[bmj0928]

I purchased the 50ppm cya standard from tftest. When I mix the standard with the new 0013 I also purchased, as directed, I can still see the dot when measuring at waist level.

 

[mknauss]

Bright sun to your back, holding the vial at waist height.

 

[Msch99]

Do you mix the standard or read straight out of bottle?

 

[cme4oil]

I don’t think you were supposed to mix the sample. It’s already a mixed 50ppm sample when you get it. You simply pour it in the comparator tube and verify you can read it correctly at 50ppm.

 

[Ripple]

I would love to get the correct answer to this. The instructions on the website say to treat the sample like "pool water." That made me think that I was supposed to mix it, which is how I tested it.

 

[laprjns]

Instructions for the CYA standard test are in the TFP Wiki here.

 

[bmj0928]

I followed the instructions, but the lighting was evening light. I'll try again today with bright sun.

 

[bmj0928]

This is the measurement at 50ppm

 

[bmj0928]

This is the measurement at 30 ppm

 

[mknauss]

Train your eyes that that is what 50 ppm looks like to you. Hard to give comment based on a picture.

 

[bmj0928]

Train your eyes that that is what 50 ppm looks like to you. Hard to give comment based on a picture.

Ok, but clearly the black dot is still visible. So, really, without training your eye with a standard first, CYA could be very inaccurate. Since chlorine levels are based on this, it
seems pretty important to get right.

 

[mknauss]

I find the dot is pretty much gone in my testing. And I can see a 10 ppm change when I add CYA of that amount.

Are you letting the sample sit for several minutes, lightly mixing it, and then doing the test? Do the test multiple times with the sample, pour it back in the squeeze bottle. Move around, hold the vial differently, etc, to see if a different method yields a better result.

 

[bmj0928]

I find the dot is pretty much gone in my testing. And I can see a 10 ppm change when I add CYA of that amount.

Are you letting the sample sit for several minutes, lightly mixing it, and then doing the test? Do the test multiple times with the sample, pour it back in the squeeze bottle. Move around, hold the vial differently, etc, to see if a different method yields a better result.

I was mixing it, letting it sit for 30 sec, mixing it again, letting it sit for 30 sec, and then testing.

In any event, my pool water measured at 100, according to the sample dot. The dot completely disappeared at 80. Either way, that's high. I'm going to do a partial drain and refill.

 

[Hootz]

I had the same experience with the 50 sample; could still see the dot. After two seasons I decided to measure the level when I could no longer see the dot. I feel that my readings are now consistent.

 

[bmj0928]

I had the same experience with the 50 sample; could still see the dot. After two seasons I decided to measure the level when I could no longer see the dot. I feel that my readings are now consistent.

I guess that's the key. If I can see it at 50 and not at 30, I'm in the acceptable range. Maybe being exact doesn't matter that much if it's within the acceptable range. Same with 80-100. That range is high, and being exact doesn't matter as much. The method to bring it down is still the same.

When it comes to SLAMming, though, I'll take the higher reading.

 

[Tres Gatos]

The only time I will ever use a test strip is to check CYA, I just can't see/figure out the dot optics (old eyes and glaucoma not withstanding). The strip is easy to use and matches what is calculated when I do a drain and refill.

 

[Dtkokay]

I had the same experience with the 50 sample; could still see the dot. After two seasons I decided to measure the level when I could no longer see the dot. I feel that my readings are now consistent.

I may be misunderstanding your post, but I thought you take the measurement at the last level you could see the dot, not the first measurement where you cannot see the dot. For example, let's assume we have a 50 CYA water sample. You should be able to see the dot at 50 but not at 40, and definitely not at 30. In that example, where you can see the dot at 50 but not 40, isn't the CYA reading 50?

For me, I fill the vial at each increment of 10. When I can no longer see the dot, I back up to the prior increment as my test result.

 

[Hootz]

What works for me is slowly filling the tube until I can no longer see the dot. At that point I look at the graduations on the tube and unless it is right on the line round up to the next highest reading. My eyes play tricks with me if I fill to each number and observe the dot...it is never consistent. The tf100 vial is a little different than the Taylor, but it is the same theory: Why Monitor Cyanuric Acid?.

 

[PoolNewb2020]

What works for me is slowly filling the tube until I can no longer see the dot. At that point I look at the graduations on the tube and unless it is right on the line round up to the next highest reading. My eyes play tricks with me if I fill to each number and observe the dot...it is never consistent. The tf100 vial is a little different than the Taylor, but it is the same theory: Why Monitor Cyanuric Acid?.

I do the same. I tried filling to specific lines few times and, like in your case, I could not get a repeatable reading. My guess is that I had a pre-conceived notion of what the reading should fall under before I even got a chance to look for the dot. Which influenced how I "saw" the dot afterwards.
By filling it until I no longer see the dot, without knowing where the reading falls as I perform the test, I get repeatable results.