Struggling with CYA

[SailorManDan]

New owner of existing 30k gal pool. Dumped lots & LOTS of liquid chlorine throughout this spring according to hardware store calculations. Started questioning and came here and read everything Purchased the TF-100 kit and am struggling with SLAM and low CYA. Pool is very clear but evidentily buring thru chlorine like a pirate drinks rum! Over past few days I've added about 15 lbs of shock (HTH Pool Care) according to Pool Math but my CYA is still 0. According to SLAM the CYA needs to be higher (to start the process) but getting confused on what should be done first. Yesterday CL = 0 and pH = 7.2. Today CL = 5 and pH = 7.2. Pool covered when not in use. Please advise. Thanks in advance.

 

[Texas Splash]

Hello Dan and welcome to TFP! Good job getting your own TF-100. So I'll mention a couple things and ask a question or two along the way.
1 -Have you added any stabilizer itself? It's typically in granule form and we use the sock pre-socking method to get it in the water efficiently. Have you done that, or have you been relying solely on the by-product of stabilizer form those HTH bags?
2 - When performing the SLAM Process, I would recommend using liquid chlorine. It's more reliable IMO when accurate dosing is required. No side effects either.

Do us a favor please. With liquid chlorine (only), add 3 gallons of 10% strength liquid chlorine. You can use Walmart's Pool Essentials as one example. Three gallons should get your FC up to about 9-10 ppm. Once you add those 3 gallons with good water circulation, set a timer and re-test the FC in 10 minutes. Report back and let us know what you get.

Don't add anything else to the water just yet. Just do that 10-min test.

 

[SailorManDan]

TS,

I thought stabilizer was stabilizer...HTH, Clorox, generic were all similar, no? Only using HTS Shock with sock treatment. Also, I'm using liquid chlorine, either 10% or 12%.

Testing: so this morning was CL = 5 & pH = 7.2. Pool uncovered all day then pre-test: CL = 1. Then added 3 gal of 10% + 10 minutes results in CL = 3.

 

[Texas Splash]

Then added 3 gal of 10% + 10 minutes results in CL = 3.

Wow, that's a huge drop. Something's brewing in that water and I don't like it. No reason for chlorine to disappear that fast. You're going to need more liquid chlorine - a lot of it to do the following:
1. Add nothing but liquid chlorine right now. Increase the FC to 10 ppm and re-test in 10 minutes. If it falls below 5 ppm, increase it back to 10 and repeat. Do this every 10 minutes until the FC shows clear signs of holding, the higher the better close to 10. That is key. You have to stick close and hit it every 10 minutes.
2. Once the FC is holding for 10 minutes (between 6-10), then you can add stabilizer. Not stabilized chlorine packets (shock) or anything like that, but pure stabilizer (Cyanuric Acid 99% - 100%). I get mine at Walmart, but Home Depot and other places have it too. Add it via the sock pre-soak method, soaking for 30 min, then squeeze it all out near the return jets.

At this point you can then increase (and maintain) the new SLAM FC level of "12" and follow the guidance on the SLAM Process.

Hope that helps get you back on track.

 

[SailorManDan]

OK, odd things going on. Before doing anything I re-tested. CL = >5. Either I'm color-blind or test liquids bad. Will re-check tomorrow morning.

Btw, my flow is 20 gpm for 20 hrs & 30 gpm for 4 hrs. Turnover is 1x 24 hrs.

 

[SailorManDan]

Texas, I believe I'm back on track after adding 8 lbs of stabilizer.

FC - 14
CC - .5
pH - 7.2
CYA - 30

It looks like I'm out of SLAM as well. Proceed normally or still more work to do with SLAM?

 

[Texas Splash]

CYA looks good. Did you pass all 3 SLAM criteria? Crystal clear water, CC at 0.5 or less, and passed the Overnight Chlorine Loss Test?

 

[SailorManDan]

Correct. Should I now bump up my CYA a bit and then start focusing on other items?

 

[Texas Splash]

Should I now bump up my CYA a bit and then start focusing on other items?

Outstanding! Yes, you certainly can increase the CYA now. Anywhere between 40-50 should work well for you up there. When you add stabilizer, remember to go back to the FC/CYA Levels and increase/maintain the FC appropriately for that new CYA as well. That's very important.

Wait until the FC falls below 10 to test/adjust the pH. You're on your way!

 

[SailorManDan]

Cool. Thanks for all your help Sensei.