Draining pool to reduce CYA, replacing water, then SLAMing

[Darron]

Hi. My CYA is off-the-charts high, so I'm about to drain the pool, replace the water, and then start the SLAMing process.

I have read the SLAM article. Just to confirm I understand the correct order of re-introducing the chemicals, I need to bring the pH up to 7.2 - 7.5 with the new water before I start adding the liquid chlorine, correct?

Historically, my pH has been low and I've been adding Borax to get it up. I'm not sure what to expect with the replacement water from the hose. I'm guessing the pH is naturally low and I'll need to actually raise it this time?

Any tips or recommendations are appreciated. This is my first time draining and SLAMing. Thanks in advance!

Darron

 

[Mr Bruce]

You can test your fill water if you are curious.

Sounds like a good plan to me! Don't bother testing anything other than FC/CC until you are finished SLAMming (pH will not be accurate with FC over 10)

ETA don't drain below a foot in the shallow end if you have a liner. You can do an exchange and not have to drop the level at all if you want.

Can you fill out your signature please?

 

[thetekgeek]

Knowing that your PH has been historically low and your CYA is off the charts high, it begs the question. How have you been adding chlorine in the past? If you were using Trichlor pucks, they are acidic and will lower PH. That could be the reason you had low PH and when you stop using them you'll get off that roller coaster.

 

[Darron]

You can test your fill water if you are curious.

Sounds like a good plan to me! Don't bother testing anything other than FC/CC until you are finished SLAMming (pH will not be accurate with FC over 10)

ETA don't drain below a foot in the shallow end if you have a liner. You can do an exchange and not have to drop the level at all if you want.

Can you fill out your signature please?

Thanks, Mr. Bruce! I will test the fill water for pH. That's a good idea.

I understand I don't need to test anything other than FC/CC while I'm SLAMing, but do I need to get the pH in-range before I start SLAMing?

And signature has been updated.

 

[Darron]

Knowing that your PH has been historically low and your CYA is off the charts high, it begs the question. How have you been adding chlorine in the past? If you were using Trichlor pucks, they are acidic and will lower PH. That could be the reason you had low PH and when you stop using them you'll get off that roller coaster.

Before I knew better, I used 3" pucks and also shocked with Clorox xTRA BLUE. This is what led to the high CYA. The previous owner also used the pucks, so they've been in the pool for years.

I just switched to liquid chlorine and have abandoned the pucks. But the CYA is so high that my chlorine won't hold....it drops to virtually zero in just a few days even when I add the Pool Math recommended amount to get it up to 5 - 8 ppm.

I didn't know the pucks lower the pH, so that's good to know. I'll test the re-fill water and see what my starting point will be. Thanks!!

 

[Mr Bruce]

Thanks, Mr. Bruce! I will test the fill water for pH. That's a good idea.

I understand I don't need to test anything other than FC/CC while I'm SLAMing, but do I need to get the pH in-range before I start SLAMing?

And signature has been updated.

Right, because you can't test for pH with high FC so you need to get that squared away first.

 

[Darron]

Right, because you can't test for pH with high FC so you need to get that squared away first.

We are about to leave for a week of vacation. I didn't want to start the SLAM process without being sure I had enough time to complete it before we left. So I've decided to do it when we get back.

Do you think there is any harm in draining the pool before we leave and having it sit empty for a week? I will leave a small amount in the deep end. In Central Texas, we are on a solid limestone base, and the pool has been there for 10 years, so I highly doubt it is going to shift.

Otherwise, my other options are to load it up with a bunch of chlorine that will hopefully last the week, or just let it go "green". Either way, I'll be draining it when we get back.

Thanks for the advice.

 

[Mr Bruce]

It's not good for plaster pools to sit empty. I would just leave it alone until after vacation.