SLAMming for 12 days and still have high CC

[mopoco]

A few weeks after my chlorine dropped to 0 while on vacation. I noticed a few algae spots in my newly refinished pebble tech pool, and I scrubbed them with a chlorine tab, but they didn't go away. I decided it's time to SLAM. I've been SLAMming for 12 days now!

CYA was at 55 when I started, so based on the table ( https://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock ) I started with FC at 24 or so. First few days the FC dropped down as low as 18, then I saw on the pool calculator that for CYA of 55, shock level is 17. Since then I've kept FC at 17 or higher except for one drop down to 15. Currently, OCLT slowly dropped from about 5 down to 2 or 1, but CC is still coming in at 2-2.5. I'm in Arizona, with no cover on pool. I pulled out the light and scrubbed in the niche even though didn't find any algae there. I cleaned the filter cartridges after about 3 days of shocking, and there didn't appear to be algae in there.

Any ideas? I'm burning up a ton of chlorine, but all the threads say to stay the course...

 

[mknauss]

If you read a CYA of 55 with a K2006 or TF100 (what are you using to test with?) then a CYA of 60 is used as we round up.

With a CYA of 60, the shock level for your SLAM is 24.

Maintain FC of 24 as often as possible. When it falls below 24 your algae is multiplying.

Take care.

 

[BasicTek]

2nd the FC of 24, and how much sun does your pool get? If it's been cloudy or you don't get a lot of direct sun to begin with I've heard the CC may take longer to go away.

 

[Donldson]

I do need to correct Marty on one thing, but only because someone else corrected me on it before and now I know Anything above the minimum FC for your CYA will kill algae faster than it can reproduce, it's just that SLAM does so much faster than minimum. So even if your FC drops below 24 you are still making headway, just slower. Otherwise he is 100% correct, round up to 60 CYA, target 24 FC, maintain as possible, etc.

As for the problem, sounds like you are SLAMing just fine, but something is causing that CC. Have you added anything to the pool recently? Generally algae doesn't cause CC as it dies, it usually indicates something else in the water. Regardless, the answer will be to stay the course as the water has something in it that shouldn't be there, but it could help prevent any future issues.

 

[mopoco]

As far as I know, nothing else in the water. Re-plastering finished in May with a fresh fill of hose water. Pool remodeler added only calcium shock and CYA, and it's been fine since then. Using TF-100 test kit for testing. @BasicTek, sun has been normal for around here... lots of it, not much shade on my pool. Thanks, I'll stay the course.

 

[mopoco]

Update. 16th day of SLAM. Daytime chlorine loss was high, so I checked CYA and it was down to 0! Surprised me, as I thought there was no way to reduce CYA except by emptying an amount of pool water. I added 32 oz CYA in a stocking in the skimmer, after it dissolved, I added 32 oz more. Not sure what the level is now, but I was shooting for 40-45. It's not zero anymore because I tested it and it was 35 or so, but not sure it's completely dissolved yet. My daytime chlorine loss is down, now, OCLT gives me no loss, but CCs are still 1.5-2.0. When this all started, the algae I saw was about 3 or 4 spots about the size of a quarter in different parts of the pool. I scrubbed those out with a wire brush, and backed it up by scrubbing with a chlorine tab. I've been brushing every day or every other day with a nylon brush. Well, I noticed the other day that one of the spots came back about the size of a dime, in spite of really high FC (I was at 24-28 with a CYA of 0). Of course I scrubbed it out again, and today I saw that that one came back again, and one of the other ones!!! Any thoughts here? Do I need to add the Polyquat that I've read about in some threads? Current readings are: FC 20, CC 2.0, CYA ~40. Another question I have is for pH. I know I cannot accurately measure that during shock process, but since it's been over 2 weeks, do I need to add some MA? I know the CYA will bring it down some, but.... Any help is appreciated. This is getting tiring, and expensive!