Very High Combined Chlorine

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Reebs

Reebs

0
Bronze Supporter
Aug 4, 2008
94
Hebron, CT
Hello!
Just starting our 13th year with our pool and I had something happen testing my water that hasn't ever happened at opening. I always expect my test results to be a little off at opening, but I have never had CC of higher than .5 before (at any time). My water is also crystal clear right now so this took me by surprise. My results are way off the norm (even for start-up). Can little to no CYA cause a falsely inflated CC reading? My results just now are below:

FC: 1.5 (however, after adding 3 drops of R-0871 turned the slightly pink water to clear, I noticed after a few seconds it started to creep back toward pink again- this is odd as I have never seen it do that. Not sure if the high CC causes this to occur)?
CC: 4
PH: 7.9
TA: 140
CYA: 0 (or close to it...the black dot was still very visible even after the tube was full (not crystal clear so there may be some CYA present, but I could easily make out the black dot).
Salt: 3600
Temp: 64 degrees.

For what its worth, readings at closing from last September 29th were:
FC: 3.5
CC: 0
PH: 7.8
TA: 160
CYA: 40

My R-0871 and R-0870 are from May of 2017 (all my chemistry is). Any suggestions as to why the abnormally high CC? Could my chemistry be bad? Does little to no CYA mess with the CC reading (I am clearly no chemist) or perhaps something has gotten a hold of my water that I haven't experienced before and this is truly accurate? Again- never had CC higher than .5.

Thanks!
 
Sounds like another case of the CYA being converted to ammonia over winter by some bacteria.

Target a FC of 10ppm, add bleach, retest FC and CC after 15-30 minutes. Rinse and repeat until the CC drop and the FC start to hold.

Then you can add CYA and start to balance things up.
 
Well, if I was going to guess I would say you won the bacteria over the winter that consumes CYA. In a perfect world that consumption is complete and you end up with "0" CYA and nothing else. In a bad world you end up with a lot of ammonia in your water. The middle ground is incomplete consumption and you have high CC.

So, are you number 2 or number 3?

How long after you added the chlorine did you get that 1.5 FC reading? How much chlorine did you add and where did you expect the FC to be?
 
Thanks for the great replies. I opened my pool on April 28th just to get it going and enjoy looking at it:). I honestly don't know what my pool guy adds on the day of opening, but I have used him for years and he is great so I am sure it was consistent with past years. I didn't test the water until today so a fair amount of time went by since he opened it. I vacuumed it the weekend of the 5th and the water was nice and clear but only tested it today as we are about a week from swimming and then realized the surprise results.

- - - Updated - - -

BTW- great to know on the water turning back to pink- never knew that before!
 
OK- so finally some progress here. After adding 726oz of 8.25% bleach over the last few days, I finally have 0 CC. However, I have only .5 FC right now. My question is do I keep it at 10 now until it holds there or aim for 4-5 which is where I normally keep it?
 
I haven't been able to spend the time needed to keep it at 10 (not able to be home for that long to monitor that frequently). I have not added any CYA yet. I will keep it high and watch it as much as I can this afternoon.
 
Reibeling said:
I haven't been able to spend the time needed to keep it at 10 (not able to be home for that long to monitor that frequently). I have not added any CYA yet. I will keep it high and watch it as much as I can this afternoon.
Click to expand...

Without any CYA, I don't think you could keep it at 10 (UV breakdown) for more then 30min? [FC/CYA][/FC/CYA]
 

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OK- With that said (and the chart) I would say you are correct. I guess I find it hard to believe that adding a jug of bleach and testing 15-30 mins later that the bleach has had enough time to circulate and give me an accurate reading of Chlorine in a 22k gallon pool?
 
Reibeling said:
OK- With that said (and the chart) I would say you are correct. I guess I find it hard to believe that adding a jug of bleach and testing 15-30 mins later that the bleach has had enough time to circulate and give me an accurate reading of Chlorine in a 22k gallon pool?
Click to expand...
That's why we test ourselves =) You can pull a sample from the area you add the bleach in if that makes you feel better ;) and compare from the farthest point. It might point out circulation issues if they aren't close =)
 
Yes- that is how I add all my chemicals:)

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If CYA measured at zero (or very close to zero), how much would you add now? Enough to take me up to TFP SWG levels or slowly at first while I am trying to get FC where it needs to?
 
Reibeling said:
Yes- that is how I add all my chemicals:)
- - - Updated - - -
If CYA measured at zero (or very close to zero), how much would you add now? Enough to take me up to TFP SWG levels or slowly at first while I am trying to get FC where it needs to?
Click to expand...

Use PoolMath to figure how much you need for the minimum, then use about 75% of that (just in case there is a miscalculation, you can ALWAYS add more, it's much harder to lower an overshoot)
Put in a sock and hang in front of return for best disbursement. If you don't backwash for a week or more, you could put it in your skimmer (the sock), but that's not as desirable, you want the CYA in the pool water, not in your filter =)

It could take a few days before the CYA will show up in the test. Just record the amount & date added and "know" that it's there.
 

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