FC Test Weirdness

[Hawk Stone]

Hello,
I'm having something rather strange happen with my TF-100 test kit.
I'm doing a bucket test (2gal pool water, 1/4 tsp bleach), and using the FAS/DPD drop test for FC.

I add the powder, then swirl, then add 4 drops of the R-0871 liquid. It neutralizes the pink color.
But then if I wait a minute, the pink color slowly comes back. I can neutralize it again with a couple of drops of the R-0871, but it will come back again.

If I can't even trust my basic FC test, I'm worried. Thank you for helping me figure out what's going on.

(background - I just returned from vacation to no chlorine, and all the CYA gone too; likely converted to ammonia. Algae starting to grow)

Hawk

 

[Richard320]

"If left sitting on the counter, the sample will turn pink again one or two minutes after the test is completed. This is normal."

Extended Test Kit Directions

 

[chem geek]

As Richard noted, this is normal. It's due either from high CC bleeding through or just from oxygen in the air getting into the water and oxidizing the DPD dye. If you didn't measure high CC, then it's most likely the latter (i.e. oxygen in the air).

 

[jblizzle]

What is this bucket test I keep seeing mentioned about adding chlorine to a bucket of water? What is the point of the test?

 

[JamesW]

It's a measured amount of pool water that you keep adding chlorine to until whatever is in the water is fully oxidized. It gives you an idea of how much chlorine you will need to add to the pool to resolve whatever issue you're trying to fix.

 

[jblizzle]

Does this then make people think they should add it all at once to the pool? Seems easier to just follow the SLAM process

 

[JamesW]

In most cases it's probably not worthwhile. It might be useful in a very limited number of cases.

 

[JoyfulNoise]

I've only heard of it (the bucket test) used when ammonia is suspected as being present. It gives you an idea of how much chlorine it will take to neutralize the ammonia and hold FC.


Sent from my iPhone using Tapatalk

 

[MarianParoo]

If you know about how much chlorine it will take to clear your pool, it can help determine the cost effectiveness of a drain and also a rough gauge of how long a SLAM may take. It is easily done, but not a test to be recommended right off the bat to all. Bucket tests can be very useful, especially for metals.

 

[duraleigh]

The point of the thread is that OP needs to SLAM the pool. We are getting him FAR off track.

 

[MarianParoo]

Duraleigh is right. Oops!

Hawk: are you familiar with the SLAM procedure? If you need help, post a complete set of test results and we will advise.
Happy slamming!