FC Test Question

JPMorgan

Well-known member
May 22, 2018
142
Elmhurst, IL
When I am testing the FC in my hot tub, the water turns light pink after I first put in the powder, but gets darker as it swirls for a few seconds. Also, when I add the drops to test the FC level it initially clears, but if I let it sit a few seconds before testing for CC, the sample starts turning pink and even red again. Do I count the drops until the sample first turns clear to get my FC reading or keep counting until it stays clear. The CC level is also quite high (4). Is that's what's causing the issue when I'm testing for FC? It's my understanding that shock level should be 10x CC. So, do I bring the FC all the way up to 40?
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
For the FC portion, you only count drops from pink to clear. Ignore what happens after it sits. For the CC, it's either time for a SLAM or fresh water. That is assuming the hot tub is separate from everything in your signature correct? When was the last time the hot tub was drained and/or had an Ahh-some treatment?

For the CC, if you chose to SLAM Process, you'll increase the FC to SLAM/Shock level based on your current CYA as noted on the FC/CYA Chart.
 

JPMorgan

Well-known member
May 22, 2018
142
Elmhurst, IL
So just to be clear on the testing for FC and CC..... I'm counting the drops of R-0871 until the water sample FIRST turns clear and that is my FC level. Then, even if the water starts to turn pink or red again after a few seconds, I continue the test for CC by adding the 5 drops of R-0003. Then, using R-0871, I count drops again until the water is clear and that is my CC level. If the water starts to turn pinkish again after it first turns clear while testing for CC, do I continue adding drops of R-0871 until the sample stays clear?

The hot tub is separate from the pool. Thanks.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Maybe this will help from the FAS-DPD Chlorine Test - Trouble Free Pool page:
For the FC:
  1. Using the small spoon shaped end of the dipper, add one heaping dipper, or two level dippers, of R-0870 and swirl to mix. If the sample turns pink for a moment and then turns clear again, or if it turns brown, add another dipper of R-0870. If the sample remains clear the entire time, your FC level is probably zero, however it is best to verify that with an OTO chlorine test, since the FAS-DPD test is prone to the occasional false zero.
    [*]Swirling constantly and counting the number of drops as you go, add R-0871 one drop at a time. Continue adding drops until the color changes to clear. The pink color may become extremely faint before it goes away. Make sure that the sample goes completely clear.
For the CCs specifically:
  1. Add 5 drops of R-0003 and swirl to mix. If the sample remains clear, your CC level is zero.
    [*]If the sample turns pink again, add R-0871 one drop at a time, swirling constantly and counting the number of drops as you go. Continue adding drops until the color changes to clear. The pink color may become extremely faint before it goes away. Make sure that the sample goes completely clear.
 

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