I thank you Sir....ordered from TFTestkits the tube and the 8oz. reagent alone with the mixing bottle, will give a good try, just looks easier for my eyes.
Help with CYA and comparing to Standard!
- Thread starter Snoufette
- Start date
I thank you Sir....ordered from TFTestkits the tube and the 8oz. reagent alone with the mixing bottle, will give a good try, just looks easier for my eyes.
ewkearns
0
Assuming, of course, that the TF-100 tube isn't the source of the, as yet unexplained, apparent errors noted in the test.
[h=2]Re: Test CYA in the sun or shade?[/h]
I really have a problem with the CYA test....I have the K2006 kit, so I ordered from TFTtestkits the larger CYA tube & mixing bottle. ordered the CYA standard 50 solution, 16oz of the R-0013 CYA and went to work.
With the standard 50 solution, I can see the dot all the way to 30.....with my pool water I still guess at my readings from 120-160 (I mix 50/50 because I do know it is high)....but I really have problems with this test.
I have tried back to sun, in the sun, slight shade, under patio, next to side of house, standing, sitting, with a cap on, without a cap, with my glasses on, with my glasses off, almost everywhere.
I did find the easiest way to see the dot, in a bright sunny day with no clouds, just inside my patio where the shade starts looking into the tube I have the best view and the lowest 'best guess-estimate' CYA readings.....with my back to the sun with light surrounding you everywhere is the hardest to see the dot and I get my highest 'best guess-estimate' CYA readings.
With the standard 50 solution, I can see the dot all the way to 30.....with my pool water I still guess at my readings from 120-160 (I mix 50/50 because I do know it is high)....but I really have problems with this test.
I have tried back to sun, in the sun, slight shade, under patio, next to side of house, standing, sitting, with a cap on, without a cap, with my glasses on, with my glasses off, almost everywhere.
I did find the easiest way to see the dot, in a bright sunny day with no clouds, just inside my patio where the shade starts looking into the tube I have the best view and the lowest 'best guess-estimate' CYA readings.....with my back to the sun with light surrounding you everywhere is the hardest to see the dot and I get my highest 'best guess-estimate' CYA readings.
So if I'm keeping track correctly, the following users all see the same problem, roughly seeing the 50 ppm standard solution reading as 30 ppm when using the TFTestkits TF-100:
Snoufette
ned8377
440dodge440
oldguy70
and the following user sees probably a different problem:
Saturn 94 (only 10 ppm difference and based on reagent so possibly not the same)
So presumably the tube in the TF-100 is the same one used in the Taylor K-1720 and the reagent is presumably the same as in the Taylor kit and so is the standard. So unless there is some sort of serious contamination in transferring reagent or standard to bottles (and it's hard to contaminate these since they are not sensitive) then if there's a problem introduced in any of these three they may be in the Taylor kits as well, from the same lot. One report seemed to indicate that the reagent was to blame (but that was only a 10 ppm error) while another seemed to indicate that the difference was with the tube at least comparing to the Taylor K-2006 tube, but that tube is less specialized than the K-1720 tube which should be easier to hold and read more accurately (and I'm not seeing any problem using that tube, but I have a little older reagent, standard, and definitely a much older tube).
Snoufette
ned8377
440dodge440
oldguy70
and the following user sees probably a different problem:
Saturn 94 (only 10 ppm difference and based on reagent so possibly not the same)
So presumably the tube in the TF-100 is the same one used in the Taylor K-1720 and the reagent is presumably the same as in the Taylor kit and so is the standard. So unless there is some sort of serious contamination in transferring reagent or standard to bottles (and it's hard to contaminate these since they are not sensitive) then if there's a problem introduced in any of these three they may be in the Taylor kits as well, from the same lot. One report seemed to indicate that the reagent was to blame (but that was only a 10 ppm error) while another seemed to indicate that the difference was with the tube at least comparing to the Taylor K-2006 tube, but that tube is less specialized than the K-1720 tube which should be easier to hold and read more accurately (and I'm not seeing any problem using that tube, but I have a little older reagent, standard, and definitely a much older tube).
So I have spoken to Dave and confirmed I am absolutely doing the test correctly. I received my replacement bottle of standard. Here is my result ...
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Still pretty visible though perhaps not quite as much as your earlier photo with the other solution. So perhaps it's not (only) the standard solution. That leaves the reagent or the tube (markings). That assumes you aren't in direct sunlight. Are you in full shade? Usually if your back is to the sun you'd see a shadow in front of you.
So what does this new solution give you -- 10 ppm lower so 40 ppm instead of the 50 ppm you expected?
Also, it was mentioned that some people shake vigorously. Don't do that. Just tilt the bottle back and forth to mix. Do not shake. you want to mix, but not aerate the solution. Maybe shaking vigorously results in excess clumping/precipitation instead of creating a consistent milky suspension.
So what does this new solution give you -- 10 ppm lower so 40 ppm instead of the 50 ppm you expected?
Also, it was mentioned that some people shake vigorously. Don't do that. Just tilt the bottle back and forth to mix. Do not shake. you want to mix, but not aerate the solution. Maybe shaking vigorously results in excess clumping/precipitation instead of creating a consistent milky suspension.
I did some follow up tests. I aggressively shook the bottle of standard solution and the bottle of CYA reagent. I then did the test and I believe I was getting much closer to the 50ppm. I did them before I read the last post, but I believe I was more gentle on the mixing once the two solutions were combined...so, it seems to be OK, but I'm not sure exactly what caused it to change.
OK so maybe there is some settling in the concentrated solutions. It is reasonable to mix them first. You really don't need to shake vigorously. Just tilting back and forth should mix them. when I was referring to shaking vs. mixing, I meant after the two solutions are combined together -- the 30 second part where one should mix them. I just didn't want too many bubbles to get into the mixture.
No I am not in direct sunlight, it just wasn't as sunny as it was the day of the first photo. Honestly I have tried this test in all light and it always looks the same to me. Also I never shake vigorously, just tilting back and forth to mix.
I only poured to the 50 line. I will mix again and see what I come up with it measuring. Although, the reason I bought the standard was to see what the dot was supposed to look like to make sure I am testing correctly.
I double checked. This is the 50 ppm standard. I don't know if you can tell but the dot is not visable. What looks like it could be the dot is reflection..
There's no chance the sticker you use to fill to is off is there? It should be 50/50. The top of my sticker is even with where the crease at the top of the bottle is. Where it changes from a straight cylinder and starts sloping in for the lid to screw to.
10 ppm out of 50 ppm would be a 20% error so yes make sure the mixing bottle marks are such that the higher mark is twice as high as the lower mark.
I'll check the measurements tomorrow... should I measure 25 mg standard and 25 mg reagent?
I think you meant 25 ml for volume. You can use whatever equal volumes you want so long as it has enough total to get to the 50 ppm mark in the CYA tube.
One more thing to try, especially if your FC level is higher, is to add some R-0007 drops to the water sample before mixing with the reagent. That will dechlorinate the water. Chlorine bound to CYA probably won't form melamine cyanurate so the CYA test could read low by as much as the FC level (worst-case).