Extremely High CC - Pool Water is Clear

pattay712

Member
Feb 16, 2020
14
Charleston, SC
I've been fighting very high CC levels for a while and can't seem to get them down. Salt Water Plaster Pool, Chemical Levels (with FAS-DPD chlorine test):

FC: 2ppm
CC: Over 20ppm (seriously, I stopped at 40 drops and the sample was still pink)
pH: 7.5
Salt Level: 3000ppm
TA: 90
CYA: 0 (I added enough this morning to get it to 30, will have to wait a day or two)

Yes, I know my CYA is 0. I did try shocking it with LC using the SLAM method for 3 days and I kept the FC around 15ppm, but I'll try again after getting the CYA up. Here's the weird thing: my pool water is crystal clear. Seriously, I don't notice any issues and don't notice a chlorine smell. I tried the CC test multiple times with FAS-DPD and DPD and they all say the same thing. Could something else be throwing the test off or is it really that high?
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome to TFP! :wave: At first I was thinking perhaps ammonia, but you stated you've been able to maintain an FC of 15 right? Is that consistently? It doesn't drop drastically at any time? By any chance have you added anything else to the water this winter? Any antifreeze, algaecides, or anything from the pool store? MPS shock products? Any chance recent heavy rains may have pushed debris or lawn chemicals into the water? I was just in Columbia this week for an Army graduation and we were soaked all week.
 

JamesW

TFP Expert
Mar 2, 2011
18,498
That level of CC is very unlikely unless you used sulfamic acid (Jack's #2 copper and Scale stuff) or your cyanuric acid was converted into ammonia by bacteria.

Have you used sulfamic acid or did your cyanuric acid suddenly disappear?

Are you sure that you're doing the test correctly?

Verify the test procedure and follow through to completion.

Try testing your tap water to verify that the test is working properly.
 

pattay712

Member
Feb 16, 2020
14
Charleston, SC
Funny you should mention Jack's #2 copper and Scale stuff. My pool underwent that treatment back in October. Could that be the reason for the high reading? My pool has had the problem with the high CC since then. The CYA level has been 0 since then as well.
 

JamesW

TFP Expert
Mar 2, 2011
18,498
Jack's #2 is responsible for the cc. Just ignore it and it will eventually go away. Just use total chlorine as free and you should be fine.

Run the test to completion to get the actual level.

Bring up the CYA to normal levels.
 

JamesW

TFP Expert
Mar 2, 2011
18,498
FC + CC = TC.

Just get your cyanuric acid level right and then maintain the total chlorine (TC) at the correct fc level.

Sulfamic acid is similar to cyanuric acid in that chlorine will combine with it and reach an equilibrium.

The bond is actually stronger than with cyanuric acid.

That's why the chlorine registers as CC.

Periodically do an OCLT to detect any excessive organic buildup.

As long as you're passing the OCLT, your total chlorine level should be adequate.
 

JamesW

TFP Expert
Mar 2, 2011
18,498
Turn the SWG off until the total chlorine gets down to a reasonable level.

Run the CC test to completion. It will eventually change. You should know the number.
 

JamesW

TFP Expert
Mar 2, 2011
18,498
It's from sulfamic acid.

The sulfamic acid is probably going away and the fc should be increasing as the sulfamic acid goes away.

Maintain the total chlorine at the correct amount and you should be fine.