FC Not Increasing After Adding Liquid Chlroine

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D

dielseman

Well-known member
Jul 1, 2017
299
GA
Pool Size
8500
Surface
Plaster
Chlorine
Salt Water Generator
Hi all, I have been adding liquid chlorine to the pool due to the low temperatures and the SWG not running. The returns are located near the sun deck. Therefore I have been slowly adding the chlorine to the deep end and mixing with a brush. However, the FC is not increasing as it should according to the pool math. What do you suggest doing?
 
PoolStored said:
How long after adding did you test?
Was the pump running?
Do you have a dolphin and was it running?
How old is the chlorine?
Where was it stored?
What is the date code on the chlorine?

Chlorine Date Code Decoder - Further Reading

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Click to expand...
How long after adding did you test? 1 day
Was the pump running? Yes
Do you have a dolphin and was it running? Not in the pool when added
How old is the chlorine? 2024 300 days
Where was it stored?
What is the date code on the chlorine? 2024 300 days
 
Where was it stored? Date is Oct 27th.
Can you post a full set of results?
What is your water temperature?
 
Last edited:
PoolStored said:
CC?
Click to expand...
This is how I am testing chlorine. I add 2 scoops of the R-0870 to the 10 ml mark. I add the R-0871 until colorless. 2 drops has been 1 FC. Do I also need to test for CC? I have not done that before. Also, where is the CC located on the pool math?

FAS/DPD Chlorine Test​

More complicated, but gives a wider range, more precision, and also separately measures FC/CC.

  1. Rinse and fill sample tube to 10ml mark.
  2. Use teeny blue scooper (hold the flat end) to put one heaping scoop R-0870 powder into sample, swirl to mix. (OK if not all dissolves.) Sample should turn pink. If it "flashes" pink then the pink disappears, add more R-0870. If there's never a hint of pink at all, skip step 3; FC=0.
  3. Add R-0871 one drop at a time, swirling the sample continuously, 1-2 sec between drops. Stop when sample turns colorless. Multiply #drops by 0.5 to get FC. (If it turns pink again after a few seconds, don't worry about it.)
  4. Add 5 drops R-0003, swirl to mix. If it remains colorless, CC=0. If it turns pink, again add drops of R-0871 (swirling continuously) until it turns colorless. Multiply drops by 0.5 to get CC.
  5. CC > 0.5 indicates a need to follow the SLAM Process.
For extremely high FC levels, you can use 5ml sample water alone or mix a 5ml sample water and 5ml chlorine-free water (e.g. distilled water) if the test is easier to view with a larger sample size; then each drop of R-0871 counts 1ppm FC/CC. This can save on test reagent.

R-0001/0002 and R-0870 powder are the same chemicals just in different forms and different concentrations. The R-0001/0002 is limited to FC levels below 10ppm while the R-0870 allows the test to be extended up to 50ppm FC. You can actually use the R-0871 drops to titrate the R-0001/0002 DPD test back to clear.[6]

How Much R-0870 Powder to Use?​

The discussion of enough DPD powder in the FAS/DPD test seems interminable. It's been going on in this forum since 2007 and probably long before that.[7]

The simple answer (no overthinking required) is if the pool water sample turns pink or deep pink, you have enough powder. Done.

So, what if the solution Doesn't turn pink? Easy again.....you have no chlorine in your pool.

A seldom seen exception to the above is when you add the powder and the solution "flashes" pink but almost immediately turn back to clear. Now you know you have very high chlorine and will need to add another scoop so the solution stays pink, then conduct the test normally.

Very often, folks are inaccurate with this test when they fail to complete it properly. The dropper for the R-0871 solution must be held vertically, drops allowed to "fall" off the dropper tip, AND YOU CONTINUE TO ADD DROPS UNTIL THE LAST DROP RESULTS IN NO FURTHER COLOR CHANGE. Subtract that drop that made ABSOLUTELY no more change and the result is the end of the test.
 
dielseman said:
Also, where is the CC located on the pool math
Click to expand...
You need to turn on tracking for CC in PoolMath.

Press the hamburger Setup in the upper right. Scroll down to Tracking and enable CC and any other optional thing you want to track.
 
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One of three things likely.
1) Chlorine has degraded
2) You have some FC demand. You have some organics going on. CC and doing an OCLT should rule this out. OCLT LINK-->Overnight Chlorine Loss Test
3) Your pool volume is off.
4) Bad reagents.

Answer these:
  1. Where did you store the chlorine?
  2. What is your CC?
  3. What is your overnight chlorine loss when you do the OCLT?
  4. How did you determine your pool volume?
  5. What pool volume did you use in pool math?
  6. What was your initial FC test result?
  7. How much chlorine did you add?
  8. What was your FC result a day later?
  9. When did you buy your K-2006 and what are the EXP date on the reagents?
 
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  1. Where did you store the chlorine? Delivered by the store. I'm not sure who they were storing it.
  2. What is your CC? I need to order this reagent.
  3. What is your overnight chlorine loss when you do the OCLT?
  4. How did you determine your pool volume? Provided by pool guy
  5. What pool volume did you use in pool math? 8,500 gallons
  6. What was your initial FC test result? Yesterday 1, today 3. I added 36 ounces of 10% liquid chlorine base off pool math. I presume you're correct and the volume I am entering being incorrect.
  7. How much chlorine did you add? 36 ounces
  8. What was your FC result a day later? 3 today
  9. When did you buy your K-2006 and what are the EXP date on the reagents? FC is new and valid
I think you're probably right about the volumes being off. As I noticed I needed to add more CYA stabilizer than the instructions said. How do I determine gallons? It is tough because of the spa and sun deck.
 
dielseman said:
  1. Where did you store the chlorine? Delivered by the store. I'm not sure who they were storing it.
Click to expand...
So you just bought it now? Then may be degraded a bit...but see FC demand below.
dielseman said:
  1. What is your CC? I need to order this reagent.
Click to expand...
Should be in your K-2006
dielseman said:
  1. What is your overnight chlorine loss when you do the OCLT?
Click to expand...
Do this and see what happens.
dielseman said:
  1. How did you determine your pool volume? Provided by pool guy
  2. What pool volume did you use in pool math? 8,500 gallons
Click to expand...
TY.
dielseman said:
  1. What was your initial FC test result? Yesterday 1, today 3. I added 36 ounces of 10% liquid chlorine base off pool math. I presume you're correct and the volume I am entering being incorrect.
Click to expand...
You added 3.3, and had demand of 1.3. (Started at 1, added 3.3 for a total of 4.3. You tested 3, so daily demand of 1.3...if degraded a bit, then maybe FC demand was less that 1.3) That is not entirely unexpected. FC demand in winter will be lower, and in summer you may see 3-5 per day.
dielseman said:
  1. How much chlorine did you add? 36 ounces
  2. What was your FC result a day later? 3 today
  3. When did you buy your K-2006 and what are the EXP date on the reagents? FC is new and valid
Click to expand...
Do the CC and OCLT. I think you are likely seeing normal FC demand.
 
PoolStored said:
So you just bought it now? Then may be degraded a bit...but see FC demand below.

Should be in your K-2006

Do this and see what happens.

TY.

You added 3.3, and had demand of 1.3. (Started at 1, added 3.3 for a total of 4.3. You tested 3, so daily demand of 1.3...if degraded a bit, then maybe FC demand was less that 1.3) That is not entirely unexpected. FC demand in winter will be lower, and in summer you may see 3-5 per day.

Do the CC and OCLT. I think you are likely seeing normal FC demand.
Click to expand...
Okay I will do that. But appears as though you're suggesting the reduction is correct. Thanks for your help!
 
You are welcome.

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