Extremely High Combined Chlorine

[TUGreystones]

Hey All, I was wondering if someone can offer a little bit of advice. We were so thrilled when we pull the cover off of our pool for the first time in six years and could see the bottom drain! I got the pump running and put 3 gallons of 12% bleach into our 16,000 gallon pool to shock it last night. When I checked the chlorine level today the combined chlorine was at 5.8 ppm!

I’m trying to figure out why the CC would be so high and how I go about lowering it. I may have exacerbated the problem by putting in 11 gallons of 10% bleach I had leftover from last season plus 1 gallon of new 12%. I didn’t realize the quality of bleach breaks down over time.

Any suggestions would be greatly appreciated. From everything I’ve read, unless I shock to 60 ppm I’m just adding to the problem. Is that correct?

Thanks!

 

[mknauss]

Welcome to the forum!
High CC is many times a sign of ammonia in the water. You have to decide if drain/exchange to fresh water is easier/cheaper than fighting the ammonia.
If you wish to fight the ammonia, follow this:
To check and defeat ammonia, if necessary, is to raise your FC in the water using enough liquid chlorine to get to 10 ppm using PoolMath. Circulate the pool for 15 minutes. Test FC and CC. If FC at 5 or below, add LC to get to 10 using LC, circulate for 15 minutes, repeat until your FC is above 5 ppm after the 15 minute circulation.

I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.

 

[Texas Splash]

Also take a moment to update your signature with all your pool and equipment info. Include your test kit. If you have any problems we'll help coach you through it.

 

[setsailsoon]

T,

Congrats on ending 6 years of no pool! If you don't have a recommended test kit. Get one asap. You'll need this to use TFP and I'd recommend the TF 100. Even if you drain and refill or exchange water you'll need the kit for regular pool care and certainly need it if you need a SLAM. Also, please do as Pat requests; add the information in your signature. Click on your screen name above right. Click again on "signature" , fill in the information and press SAVE. This will help us get answers to you as fast as possible.

I hope this helps.

Chris

 

[TUGreystones]

Thank you all for your help! Apparently my massive shock with old chlorine did the trick! When I was able to recheck levels today the combined chlorine was gone! I filled my chlorine feeder with 6 tablets and turned it on high. There was zero chlorine in the pool when I checked. Levels are as follows:

FC=0
CC=0
TC=0
CYA=0 (or at least under 30)
TA=70
C=somewhere between 70-90 (it was dark outside by the time I was able to run the test, and the color started out as purple)
Temp=60? (don't have a thermometer in yet, but it's cold outside in SE Indiana)

What would you all recommend doing next? There's a good amount of algae or dust/pollen in the pool stuck to the liner, though the water is fairly clear and blueish. We're going to vacuum to waste but haven't had a chance to do so yet - meaning I don't want to put a ton of chemicals in before I do that.

Thanks, again for the insights; they're greatly appreciated!

 

[TUGreystones]

Sorry - put my signature in the wrong place. Hopefully I got it this time

 

[mknauss]

Pull the pucks, add 20 ppm CYA granules using the sock method, check your pH and lower to 7.2 and SLAM Process

 

[TUGreystones]

Oops! Forgot to add my PH - it's at 7.0. Should I try to raise it up? Also, could you explain why to pull the pucks? I'm not arguing just wanting to understand so I know what to do in the future. Again, I greatly appreciate the help!

 

[mknauss]

Pucks add FC and CYA, slowly. You need FAST to kill the algae.

pH of 7 is fine.

 

[TUGreystones]

Great! Thanks so much!