Small levels of CC - Also quick q on FAS-DPD test

sws1

Well-known member
Aug 13, 2010
55
Neptune City, NJ
Hi - I'm a 10 year pool owner who has been quite successful using all the techniques I've learned here.

I just moved to a new house with a different pool and have some questions on things I see that are a bit different.

The new pool is ~29k gallons and currently has these specs:
Water is clear, and has no smell.
CYA 50
TA ~130
FC is around 6 (depending on when I check)
Temp is currently 59 degrees.
I use 12% liquid chlorine.
DE filter
Pool was opened exactly 1 week ago, and was pretty clear in about 2-3 days.

So, spring opening is done and with the exception of the following, I'd say it's ready to go.

However, when I do a CC test, it says I have a reading of about 1. Definitely not 0 like I always had at my old pool.

NOTE - This new pool is in a yard surrounded by trees. There is alot of pollen, and little leaves still falling in the pool, because the trees haven't quite reached full opening. Not enough to change the color of the water, but the water edge has alot of tree crud.

Questions -
Is the CC number of 1 likely related to the tree junk?
Is it the ratio of 1 CC to 6 FC that is important? Or the absolute value of 1 CC that is more important? (I read somewhere that a 1:6 ratio may not be that big of deal and is normal. In my old pool, I often had a lower CYA reading. I may have overshot a bit on the CYA this year.)

Not sure if I need to do anything with this, other than monitor it to see if it goes down when the trees stop dropping their crud.

LASTLY - A side question - When I do the FAS-DPD test, the color goes from red to clear with 1 or 2 drops, but then comes back to red VERY slowly. i.e., After the first couple drops, I'll add some drops, stir, and the water looks clear. Wait 30-60 secs and the red slowly reappears. I don't recall it taking THAT long for the color to re-appear at my old pool.
Could my powder or chemicals be old? Is that my TA that is causing a slow response? Water temp?

Thanks
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,694
Laughlin, NV
CC is a result of ammonia based organics being consumed by the chlorine. Or a non-chlorine shock was used in the recent past.
Monitor, but do not over react. If FC loss is as expected and water clarity is good, no reason to address

Never heard anything about a FC CC ratio. Not a TFPC article I suspect.

When you do a FAS-DPD FC test and CC test, the entire test must take under a minute. Do not wait. The chemistry of the test will bring back the red color if you let the sample sit.
 

sws1

Well-known member
Aug 13, 2010
55
Neptune City, NJ
CC is a result of ammonia based organics being consumed by the chlorine. Or a non-chlorine shock was used in the recent past.
Monitor, but do not over react. If FC loss is as expected and water clarity is good, no reason to address

Never heard anything about a FC CC ratio. Not a TFPC article I suspect.

When you do a FAS-DPD FC test and CC test, the entire test must take under a minute. Do not wait. The chemistry of the test will bring back the red color if you let the sample sit.
Thanks. So is it possible I am not getting a FC reading of 6...because I'm letting it turn back to red before I add more drops? I'll try again, but from memory, it was at about the 4th drop where the color would turn clear quickly...but come back to red in about 15 secs.

By comparison, the other chlorine test (with the yellow colored water measurement) doesn't show anywhere near 6. It was showing a much lower number.
 

Razorhog

Bronze Supporter
Jun 20, 2013
711
Northeast Arkansas
As far as I know, when the color goes from red/pink to clear is when you record the number. Whatever happens to the sample after that is irrelevant. If yours went clear after 1 or 2 drops, your FC is too low. Do you have a SWG?
P.S. - put the info about your pool in your signature so it's easier for folks to help you troubleshoot, and you don't have to type it out each time you post.
 

sws1

Well-known member
Aug 13, 2010
55
Neptune City, NJ
OK - So I redid the test...quickly. It showed FC of about 2ppm, and CC of about 6ppm. (I didn't pay too much attention, once I realized it was going to be high.)

I added 5 gallons of 12% chlorine, stirred it up, and tested about 10 mins later: FC of 10, and CC of 13+ (I was quite shocked by this result. Sounds like all my fresh chlorine was getting immediately turned into CC.)

So added another 4 1/2 gallons and will test in a bit, to see if I can get the FC above 20 (which is the target for CYA of 50).

(I had assumed that clear water would indicate that I wasn't going to have a CC issue.)

More to come.
 

sws1

Well-known member
Aug 13, 2010
55
Neptune City, NJ
I was able to get my FC up into the mid-20s. And the CC was still quite high (13 or so - I get a different set of numbers every time I do it). Higher than it was when I didn't have enough FC in the pool.

Will the CC's dissipate? Or am I making the issue worse?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,694
Laughlin, NV
That high of CC is very suspect. Be sure you are using the correct reagents and following the correct testing protocols.
 

sws1

Well-known member
Aug 13, 2010
55
Neptune City, NJ
That high of CC is very suspect. Be sure you are using the correct reagents and following the correct testing protocols.
Something is definitely not right. I just got readings of 21 FC and 11 CC. The other strange thing is that my OTO chlorine test only shows a Total Chlorine of 1. Wacky.
I looked at the TFTTESTKIT website, and it said that the DPD reagent #3 needs to be clear. Mine is bright yellow. Even 1 drop causes the color to change immediately. So, I'm gonna order a new refill kit.

Until I get the new kit, I'm going to assume my water is fine. It's spotless, and has no smell at all. And now that I've superchlorinated it today, the odds are that it's fine.
 

sws1

Well-known member
Aug 13, 2010
55
Neptune City, NJ
How has this kit been stored and how old are the reagents?
I had an old kit from 8-9 years ago. I replaced all the chemicals about a year or so ago, although I see 2019 expiration dates on some of them.
They were stored in my sunroom. Either in the plastic case, or the plastic bag in which they were shipped.
 

sws1

Well-known member
Aug 13, 2010
55
Neptune City, NJ
I tested the FC last night just before sun went down. It was around 20. Added another gallon of 12% chlorine.
Measured first thing this morning, and the FC is at 10. With my outdated and yellow chemicals, it was still showing CC at 13.

Water is spotless and odorless though.

Does this sound like an issue with my testing, or the water? The numbers seem to be all over the place.

EDIT: See my next post for clarification.
 
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sws1

Well-known member
Aug 13, 2010
55
Neptune City, NJ
OK - I think I got it. In the test I just posted above, it occurred to me that I wasn't adding enough of the powder into the liquid before I started the drops. (I read that 1 scoop is enough for low FC, but when FC is over 20, I realized I wasn't bonding all the chlorine with 1 scoop.) So I added 2 large scoops and redid the test. Water was much more red.

FC is 24 or 25 (which equals the 20 I measured last night plus 4.3 from the added gallon of chlorine.) So no FC loss.
AND, when I added the 2nd reagent, it showed NO CC.

So, I'm going to say I'm good, although I will retest when I get the new batch of chems.

Thanks for the help.