FAS-DPD Test Question

[RockstarSD]

When I perform this test, I do the following.

1) Add a serious scoop of the powder. It's probably 3 to 4 times the amount of the "heaping" scoop in the TFTestKit video on how to do the test.
2) Swirl for 30 seconds or so until the water is a nice hot pink
3) Add R381 one drop at a time until the water turns clear, swirling 5-10 seconds between drops

Now here's where my question comes in. In most of my tests the water will turn clear and stay there for a second or two, but then by the time i put the sample down, grab the next bottle to test for combined chlorimines, the original sample is pink again. How long am I supposed to wait between drops to confirm a true "clear" test reading? 1 second? 5 seconds? 30 seconds?

I only ask because the water first turns clear MUCH lower than I think my FC should be reading, and then it takes a lot of swirling (more than 5 seconds usually but less than 30) to get the pink to show back up so that I can add another drop... I'm really confused on this test. I should also point out that I'm shocking too, so that may have something to do with it.

Thanks!

 

[JasonLion]

First, if the FC level is at all high you need to move more quickly than that. You should be able to average one second of swirling between drops or less until you are getting towards the end. Adding drops too slowly when either FC or CC are fairly high will result in false high readings. What matters is the total time, so you can go more slowly when both FC and CC are lower.

Second, the sample will always turn pink again if you leave it alone long enough, certainly within a minute or two, often more quickly. You only need to see 5 to 10 seconds of clear and you are done.

 

[J20832]

Remember, at high chlorine levels (like when shocking), it is important to move through the testing quickly. It is normal for the pink color to return after sitting for a minute. Also, I think you are probably just wasting the powder using more than 2 scoops.

Check out the extended directions for FAS-DPD

http://www.troublefreepool.com/extended-test-kit-directions-t25081.html

 

[RockstarSD]

Thanks guys. I read the extended directions but still felt the need to ask the question. Next time I test I will try to add drops less than 1 second apart. Thanks a bunch!

 

[JamesW]

What is your CC reading?

Are you using any MPS (non-chlorine shock)?

 

[RockstarSD]

I have been using 12.5% chlorine liquid exclusively for 4 days and 6 hours.

prior to that there was cal hypo shock, dichlor shock, and trichlor pucks, but no non chlorine chemicals unless they were used by the previous owner and there was no evidence of them at the property.

 

[RockstarSD]

23 test results are in the new homeowner green pool thread in the algae forum. my entire process for the last 4 days documented from start till now.

 

[crek31]

FWIW, I love, love, love the Speed Stir. Seems expensive at first, but after initial use I'd never be without it. And, welcome from another Nebraskan -- I'll have to look at a map, not sure where Kennard is.

 

[RockstarSD]

I'm about 20 minutes or so north west of Omaha. My address is kennard, but I'm not actually in the town of kennard.

 

[YippeeSkippy]

When I perform this test, I do the following.

1) Add a serious scoop of the powder. It's probably 3 to 4 times the amount of the "heaping" scoop in the TFTestKit video on how to do the test.

If you're over adding the powder when its unnecessary you'll just run out of it that much sooner. I don't believe it improves the quality of the test.
The speed stir is a nifty tool. I did without it until recently but find it does speed up the testing process. I was a Dang good swirler and tester but sometimes wanted a free hand so it helps there. I have a friend here who is apparently a clumsy swirler and has stains on her hands from getting the reagents all over her. She NEEDS the speedstir just to keep her hands clean, LOL.