PH low before SLAM

[Drhuber]

Hello,

I am new to this site and trying the methods outlined here. I have a Taylor K-2006C test kit with the following results.

FC = 2.6
CC = 2.4
CYA = 50
TA = 200
CH = 180
PH = Below 7.0

Based on my CC I was going to SLAM the pool. My concern is that my PH is too low to start the SLAM. When I tested PH and did the base demand test (reagent R-0006) it took 20 drops to get my PH up to 7.2. The chart within the Taylor guidebook only goes up to 10 drops to calculate the amount of sodium carbonate that needs to be added. My pool is around 17,000 gallons. At 10 drops I should add around 6 lbs of sodium carbonate but I'm at 20 drops. I tested my water at a pool store 4 days ago and my PH was at 7.0. I'm not sure how my PH could drop so quickly. Does this seem right?

How imperative is it that I get my PH to 7.2 before I start to SLAM?

Thanks!

 

[mknauss]

Welcome to the forum!
A pH below 7 and a TA of 200 ppm is not chemically compatible. pH only drops by adding acid or acid items, such as trichlor or dichlor.
I suggest you carefully redo the TA test and confirm that level. If correct, the pH will rise very quickly.
Your CC is very high. Have you added any chemicals that can effect that (sulfamic acid, monosodium persulfate (non chlorine shock), etc?
I suggest you read ABC's of Pool Water Chemistry.

 

[Drhuber]

Thanks for your reply. I just reperformed the TA test and received the same results (200ppm). I have trichlor (chlorine tablets) in the skimmer. In the past few weeks I have done three phosphate treatments (not sure what chemicals were in those treatments) based on the pool stores recommendation. That was before finding this site. I have read through the ABC's of Pool Water Chemistry.

Should I go ahead and begin the SLAM process? Even if my PH is low and TA is high?

Thank you!

 

[mknauss]

The trichlor is very acidic and should never be placed in the skimmer. I do not know if you have a heater, but it is being compromised by those being in the skimmer.

The trichlor could be lowering the pH. Discontinue its use now and the pH will rise quickly.

 

[Drhuber]

Hello,

I was able to get my ph up (7.2) before starting the SLAM. I started this morning with a FC level of 0.6 and a CYA of 45. My SLAM Target FC is 18ppm. Here is the time frame of adding chlorine based upon my pool (17,000 gallons). I have been using Pro-Clor Pool Shock from Menards which is 12.5% sodium hypochlorite (128 oz).

7:00am (0.6 FC) - 2.4 jugs
1:30pm (3.8 FC) - 1.9 jugs
3:30pm (4.2 FC) - 1.9 jugs
6:00pm (2.6 FC) - 2.1 jugs
8:30pm (5.5 FC) - 1.7 jugs

I have used 10 jugs of chlorine in day one of SLAM. Is this normal? Also, I'm not really decreasing the amount of chlorine I've added each time much.

Thanks for the help!

 

[mknauss]

Sometimes your organic load is large. The high CC implied that. Stay at it. I would suggest you round up your CYA to 50 ppm. You cannot measure a CYA of 45 with the test method used.

 

[Drhuber]

Thank you. My pool water is crystal clear with no visible debris. Can my organic load still be that high?

 

[Bperry]

Thank you. My pool water is crystal clear with no visible debris. Can my organic load still be that high?

See if you can find out what the “phosphate treatments” were and review post #2. If your CC really is that high then yes the organic load will be high. But if you added any anything like non-chlorine shock, etc those interfere with the CC test.