At my wits end - after 3 SLAMs

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R

run53

LifeTime Supporter
May 4, 2010
410
TC=9.5
FC=9.5
TA=70
pH=7.6
CH=180
CYA=70


I've been through 3 SLAMs this summer and each time, I pass all 3 tests. The last time (one week ago) I kept SLAM levels (20ppm) for 4 nights and made sure I passed OCLT all 4 nights before letting it drop. Water was sparkling until this morning. It's still very clear (no trouble seeing specks at bottom of 8' deep end), however it doesn't sparkle like it did yesterday (and all the days since the last slam a week ago). Am I being anal? I'm sure most people would think my pool is fine but I can tell the difference just by looking.

It's the same pattern....about 7-10 days after each SLAM (seems like when FC drops below 10 for a few days), I notice the sparkle goes away. Could it be possible my FC needs to stay above 10? Is there something else at play here?

Additional info:
I added CYA over the last couple of days to get levels from 60 to 70. Last measured CYA was 60, so I'm amusing it's now 70 even though I can't read it for a week or so.

I've been testing my water 2-3 times per day and I absolutely know that FC has not dropped below target. This morning it was 9.5.

The other thing I've noticed is that previous years, my pool needs Muriatic acid at least once a week. I've used very little acid this year. I think I only added it once. Yet the pH stays in the 7.4-7.6 range.

I removed the skimmer plates and the return directors and cleaned with a toothbrush during the last SLAM (yes there was some algae there but now it's gone). I also dove to the bottom and did the same to the main drain.

One last thing....I am pretty sure I have an iron staining problem as I tried rubbing some vitamin C on the liner where it has discolored a bit and it goes away. I was going to do the ascorbic treatment in the fall before I close.

I am providing all the above in case it helps figure out what is going on with my pool. I just can't figure out what is going on and 3 successful SLAMs doesn't seem to solve it.
 
Assuming your CYA was 60...if you maintained a SLAM FC of 20 ppm then you are not performing the SLAM correctly. You should be at 24 ppm and at a CYA of 70 you should be at a FC of 28.

As for your pH, it appears you have found a sweet spot...I wish I could keep my pH between 7.4 - 7.6, muriatic acid fumes bite.
 
I would agree if you did a SLAM at 60 Cya it likely didn't get done. Or maybe you have higher Cya than you think. If you are getting cloudy after several days like that, it really just sounds like lack of Chlorine.
 
What calculator are you using? Pool Math gives me a shock value of 24ppm for a CYA of 60ppm and 28pm for 70ppm CYA. But that really doesn't matter. The end result of clear water and passing the OCLT is the important thing.

Maybe something else is going on. Do you see FC level variation when you start to notice the problem? Any correlation with filter backwashing? Have you inspected the inside of your filter to verify there isn't a problem? Tree pollen? Not saying any of these are likely. Just throwing out ideas.
 
Do you have a picture of your water we could see? before and after would be great! I don't know if the experts would agree but you could take your FC to mustard algae shock levels for 24 hours. I think the FC at CYA of 70 would be 41 ppm.
 
JohnT said:
What calculator are you using? Pool Math gives me a shock value of 24ppm for a CYA of 60ppm and 28pm for 70ppm CYA. But that really doesn't matter. The end result of clear water and passing the OCLT is the important thing.

Maybe something else is going on. Do you see FC level variation when you start to notice the problem? Any correlation with filter backwashing? Have you inspected the inside of your filter to verify there isn't a problem? Tree pollen? Not saying any of these are likely. Just throwing out ideas.
Click to expand...

Here is the pool calculator that says 20ppm schock for CYA=70 and yes, I agree, the important thing is Clear water, OCLT and CC tests all passed with flying colors for 4 straight days of SLAM.

You may be on to something with the filter. I will investigate further today and report back.
The Pool Calculator

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jaduck said:
The chart is correct. I did not know that Pool Math gave a Target Shock level, are you using a calculator app?

Three test:

CC less than 0.5...check
Pass OCLT....check
Water Crystal Clear...???
Click to expand...

Yes....all three passed with flying colors for 4 straight days of SLAM. About 5 days later (i.e this morning),the sparkling went away.
 

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I just looked in the skimmer and there is like a grayish blackish silt floating on top. I will take a picture and post it here soon. It also rained a bit last night, in case it matters.
 
The definition of a finished SLAM is to complete the OCLT and pass that.

Once your water loses it's sparkle, see if you can pass the OCLT again. If you do, that means you have nothing organic in your water causing the dullness.

You are left with the inescapable conclusion that your filtration is inadequate........either in run time or perhaps something not performing correctly with your filter.

There is nothing in your pool that is any different from anyone else's so run that OCLT and, if you pass it, maintain your chemistry as you have been and start to look at your filtration system.
Is there something else at play here?
Click to expand...
No, pools and pool chemistry are not mysterious. The principles apply universally.
 
zea3 said:
Are you using bleach or SWG for chlorine?
Click to expand...

I use SWG for normal use and Bleach for SLAMs

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Texas Splash said:
For future reference, here is the correct calculator: Poolmath calculator .

Good luck!
Click to expand...

Thanks. I somehow had an incorrect link to another calculator that appeared to be associated with TFP

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jaduck said:
When did you clean/recharge your filter last? Gosh, I am fresh out of suggestions...sometimes crystal clear can be so frustrating.
Click to expand...

I have a DE filter. No backwashing, I just clean/recharge when it gets to 18-20 psi. Last clean/recharge was about 4 weeks ago. Usually I only do this about 3 times a season.
 
Here are the pictures of what I found floating in my skimmer this morning.......you can see the blackis silt floating on top

pic1.jpg


Then I stuck my finger in and it clinged to my finger....................

pic2.jpg


Not sure what this was or where it came from. Possibly the filter has a leak or one of the fins of the cartridge is torn?
 
Here are a couple of pictures of the water from this morning. Even if I had a picture of yesterday when it sparkled, I don't think you would be able to tell the difference with a photo. I can just barely tell with my eyes. But like I said, I am anal.

pool2.jpg

pool1.JPG
 

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