CYA levels off the chart?

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Yes... I think the usual practice is to pour it back into the bottle you used to mix pool water and reagent... then pour it into the graduated cylinder again. Basically repeating the "pour it until the dot disappears" part without using any more reagent.
 
Well, without redoing the reagent part, would you not always get the exact same result....by pouring back your result from the graduated cylinder back to the bottle and then back to the graduated cylinder, why would the result be any diff? Am i missing something very obvious? :confused:
 
You want to get the same result. You are verifying that you saw it correctly, which with this test is a very real concern. 90+% of the errors with the CYA test are vision errors.

Sent from my HTC Thunderbolt.
 
Exactly. Figuring out when the dot disappears is the variable part -- different testers, different light conditions etc... all make a difference.

Think of it as the only test where you get a free do-over if you think you poured a bit too much into the cylinder and missed the dot disappearing :D
 
Savantgary, that is what I understood, and it makes sense. It is still the same solution that you are reentering the black dot tube, and it gives you another chance to "decide" when the the dot disappeared....btw when I had the tube on my dark teak counter top the dot disappeared sooner, than when I held it. More light from the bottom allowed the dot to stay visible longer. Just that one variation in testing yielded a 25ppm difference. I have emailed Taylor to get their input....25ppm million is a big variation.
 
thanks RobbieH,

Just got off the phone with Wayne (tech dude) at Taylor. And I have an old (2yr) style comparator tube that is not CYA reading friendly. So I will wait for my new K2006 delivery today to see if it has the "squared off" tube that has the CL range of .5 to 10 vice the .5 to 5 that the old tube has.

The video from Taylor has tube setting on dark surface and the TF Kit instruction says to hold at waist level with sun behind you, I assume to decrease the reflect light from entering bottom of tube.

Now that I am buying into chem geek's cya/fc relationship notion, it seems to me that the important number (CYA) that is provided by either the K2006 or TF 100 is real "fuzzy". One in which the recommendation is to have several "do overs" by several people and average the results.

I am looking into the larger tube with a stick that you pull up and push down the tube. Update: (Plunger stick and beaker only saves you from using a 2nd container to re-evaluate the sample, uses more reagent, costs more )
 
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Consistency/Repeatably is not necessarily equal to accuracy. My results given earlier were within 10-15%(according to Taylor Tech normal reading variability) of each other using the same background:

1. Tube on dark counter top--under roof yielded 60 & 70 (65 average)
2. Tube held and sunlight reflected off of deck--no roof yielded 90-100 (95 average)

FC target for condition 1 above= 7.5
FC target for condition 2 above= 11.5

That is a big difference in chlorine!!
 
We understand that the CYA test leaves something to be desired, but the melamine–based turbidity test is the best we have available.

If you have complaints about consistency/repeatably, take samples to 5 different pool stores and see what each of them tells you for CYA.

There is a 50ppm CYA Standard solution that you can purchase at TFTestKits, which allows you to train your eye to what the disappearing dot should look like.
 

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svenpup said:
We understand that the CYA test leaves something to be desired, but the melamine–based turbidity test is the best we have available.

If you have complaints about consistency/repeatably, take samples to 5 different pool stores and see what each of them tells you for CYA.

There is a 50ppm CYA Standard solution that you can purchase at TFTestKits, which allows you to train your eye to what the disappearing dot should look like.
Click to expand...

svenpup,

The variance I had in lack of a trained eye was 10ppm, avg the two and that yields a .5-1ppm difference in FC (no problem).

The variance because of background was 30....that is a 4ppm Target FC differential and 10ppm FC for shock....that is a big difference
 
You should hold the tube in front of you with your back to the sun so that you are shading the tube and looking straight down into it. That is strong indirect light which is the kind of lighting used in calibrating the tube. As was mentioned, you can also buy 50 ppm CYA Standard Solution to practice. You can pour the solution out of the CYA tube back into the bottle, back and forth for practice seeing when the black dot disappears. I find the test to be very consistent and reasonably accurate when done in proper lighting conditions.
 
Thanks Tim5055 for the advice. It appears that my biggest problems are an outdated comparator and inconsistent reflected/indirect light.

My wife has to read the chlorine test results, I can't distinguish the reddish colors.....my FAS test arrives tomorrow

Thanks Chem Geek, my 50% test standard solution was ordered., I will find the correct lighting conditions.
 
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