Testing technique questions

[ScudBar61]

Hello
I’m trying to make sure I’m getting the best results, so I’m trying to refine my techniques. Using a Taylor K2006 test kit , Taylor 9198 tubes (one for each test except CYA and Ph), magnetic stirring bars and a magnetic mixer. I clean the tubes and stirring bars with pool water before and after each test. I just read about cleaning reagent bottle tips with a cloth before dropping.
My questions:
1). Saw one post about using bleach to clean tubes and stirring bars—is that necessary?
2). Another poster labeled their tubes and stirring bars and used the same tube/bars each day for the different tests.—does that lead to better accuracy?
3). Another post talked about the FC FAS-Dodgers test and said to subtract one drop from the total drops necessary to take the solution to clear. Is the actual FC level a multiple of the total drops required to clear, or total drops minus one?
Thanks!

 

[proavia]

Extended Test Kit Directions Archives

www.troublefreepool.com

1 - Not every time. If you think the result is off or see residue in the tube, clean with bleach or alcohol.
2 - Not necessarily.
3 - FAS-DPD - use the 10ml sample size and one scoop of R-0870 - add drops until clear. Count all those drops.

Try not to over think it.
We aren't making rocket fuel.
Close is close enough.

 

[Newdude]

+1. A good rinse after is all you need. Any leftovers may skew the next test. I use one vial and speed stir bar for all the tests that call for it, but we all have our ways and nobody is wrong.

 

[DrewLG]

I’m trying to make sure I’m getting the best results, so I’m trying to refine my techniques. Using a Taylor K2006 test kit , Taylor 9198 tubes (one for each test except CYA and Ph), magnetic stirring bars and a magnetic mixer. I clean the tubes and stirring bars with pool water before and after each test. I just read about cleaning reagent bottle tips with a cloth before dropping.

Be careful cleaning reagent bottle tips. They're manufactured to give precisely sized drops (25 drops per mL, +/- 1 drop), and any distortion, abrasion, contamination, etc., could affect the drop size and therefore affect your results. It's ok to wipe around the tip, but don't wipe over it.

Inaccurate water-sample sizes will also affect your results. How are you measuring your pool-water samples? Consider using a Taylor SampleSizer if you aren't already. With your 9198 vials it'll provide very quick, very consistent 10- and 25-ml sample.

1). Saw one post about using bleach to clean tubes and stirring bars—is that necessary?

I don't think so. When I got a full refill set of reagents earlier this year, I did a test with my old reagents and then cleaned the vials with alcohol and tested again with the new reagents -- no difference.

My usual routine doesn't involve any cleaning with alcohol or bleach. I rinse the vial and stir-bar twice with pool water before each test, then thoroughly rinse them with tap water (I do my testing indoors) after each test.

 

[ScudBar61]

Thanks for the replies and suggestions! So much to learn

 

[Bperry]

Is the actual FC level a multiple of the total drops required to clear, or total drops minus one?

You count all the drops and divide them by 2 to get the FC result.

 

[ScudBar61]

DrewLG
Agree on the samplesizer. Bought one a couple of months ago

 

[Griswald]

I think you are overthinking this process. Just be consistent and fairly clean and you'll be fine.

 

[mgtfp]

3). Another post talked about the FC FAS-Dodgers test and said to subtract one drop from the total drops necessary to take the solution to clear. Is the actual FC level a multiple of the total drops required to clear, or total drops minus one?

What might have been meant here is probably this: If you are not sure if it is already clear, then add another drop. If this drop doesn't change the colour any further, then don't count this last drop. What's important is that there is no pinkness left, it may remain a bit cloudy. "Clear" means "not pink" in this test.

If there was still some pinkness after 9 drops and it's colourless after drop 10, then we know that FC must be larger than 4.5ppm, but not larger than 5ppm. We call this 5ppm.

Do the test fairly quickly, once the pink has gone after a quick swirl the test is finished, discard the sample. If you leave the sample sitting on the bench after that, it may turn slightly pink again after a while. This is normal, don't keep adding drops.

Just out of curiosity: Did autocorrect turn "DPD" into "Dodgers"?

 

[ScudBar61]

You gotta love autocorrect—yes it did! Don’t ask me how it got there