Is my water balanced while SLAMing?

[JABRY5]

Started SLAMing 5 days ago and duking it out with a feisty bloom.

Before starting, my water was very close to balanced:
CYA - 40
TA - 100
CH - 250
pH - 7.5
Temp - 75F

Been trying to keep my FC levels between 16 and 24, which my understanding from ChemGeek's chart is the "safe harbor" SLAM range based on a CYA reading of 40.

My question is: how do I know if my water is balanced while SLAMing? I can tell this is going to be a couple of weeks before I am done...and don't want to unknowingly damage any equipment. For what it's worth, I am using cal hypo granules for this particular SLAM.

I appreciate reading other SLAM stories. They are like group therapy.

 

[JJ_Tex]

The main test you should do is FC while you are slamming.

The only thing I would watch would be your calcium since you are using Cal Hypo to SLAM. By my math 1lb of Cal Hypo will raise your calcium by 3, so if you have a 50 lb bucket that will raise it by 150. If it starts creeping up, you can easily switch to liquid chlorine.

 

[JABRY5]

Agreed, I will be watching calcium closely. PoolMath recommends anywhere from 350 to 550 as "ideal," so I figure I have a ways to go.

 

[Richard320]

During the SLAM, you only worry about FC. That said, JJ is correct about CH climbing. But all you can do to lower that is replace water, so let's not get sidetracked.

You target 16 FC for 40 CYA. Going to 24 is wasteful. The higher the FC, the greater the percentage lost to the sun. It's better to add 4 FC three times than 12 FC once. Again, let's not get sidetracked explaining that, just know that you don't need to go that high. If you have mustard algae, you clear the pool normally and then go up to 24 for the last bit. If you don't have mustard algae, don't bother.

The SLAM process shouldn't take weeks. I still think the record for an all green pool to pass all three tests was three days, but he was obsessed and got up every couple hours during the night to test and dose. A foul-smelling black sludge pit can be cleared in less than two weeks. What is key is regular dosing ( every few hours) and brushing until your shoulders and back can hardly take it anymore. And look for hiding places. Behind lights. Beneath ladder rungs. Inside the skimmer throat. I collected some good SLAM threads and some other stuff here. I know a lot of the pics disappeared, but still some good stuff. Recovering my old inspirational links

 

[JABRY5]

Thanks for the detailed explanation. I've been told in the past that a sand filter can take 2 to 3 weeks to clear the pool during a SLAM. Is that not true?

Is it the case that my water won't be more or less corrosive / scaling because of the SLAM? Or is it that the SLAM only takes a few days, so we don't worry about it?

 

[Richard320]

Thanks for the detailed explanation. I've been told in the past that a sand filter can take 2 to 3 weeks to clear the pool during a SLAM. Is that not true?

Is it the case that my water won't be more or less corrosive / scaling because of the SLAM? Or is it that the SLAM only takes a few days, so we don't worry about it?

A green sludge pit could take three weeks to filter clean with just the sand filter. Once it's stopped devouring bleach like crazy and you're just waiting for the filter, you can add some DE to the sand filter and get filtering almost as good as a straight DE filter. With the corresponding need for frequent backwashes.

The reason you don't worry about the rest is because the pH test can get skewed by high FC levels. TA is not critical and shouldn't be changing much anyway. Unless you're adding CYA, it won't be changing (you'll lose a little with backwashing) and the same goes for CH. Besides, once the pool is cleared and you can test and adjust everything, it all can be brought back into range in a couple hours. It's the algae killing that requires diligence.

 

[JABRY5]

Thanks. This really helps. I have noticed my first tinge of blue, which is a comforting guidepost. It seems like the color of the pool is ahead of the cloudiness, if that makes sense.

 

[Richard320]

Thanks. This really helps. I have noticed my first tinge of blue, which is a comforting guidepost. It seems like the color of the pool is ahead of the cloudiness, if that makes sense.

It makes perfect sense. The progression goes black>green>grey>blue>clear. Not everyosone starts at the same place.