High pH with SWG and adding CO2 system

[nofears]

Hello, my first post here so thx for having me...I just built a small 5K gallon salt pool in AZ. pH continues to run above 8 every few days even after adjusting with MA. I've decided to add a PoolSmith CO2 system into my equipment tomorrow to see if it helps stabilize pH around 7.5 to 7.6. I will have two 20lb tanks and they should last about 5 months. I will report back with install pics and results.

ing this works

 

[mknauss]

Welcome to the forum.
I would not install a CO2 system. The TA being added by your fill water due to evaporation will still require acid to be added quite often. Better to install a Stenner pump and tank to inject acid if you wish more automation.

 

[nofears]

Welcome to the forum.
I would not install a CO2 system. The TA being added by your fill water due to evaporation will still require acid to be added quite often. Better to install a Stenner pump and tank to inject acid if you wish more automation.

Thanks so much for the fast response! I appreciate your opinion and suggestion but I don't have an issue adding acid to reduce alkalinity...I need a more stable pH as my pool keep going out of balance every few days. I'll add acid to adjust alk as necessary...which I'll determine as time goes by if the CO2 system works.

 

[mknauss]

Great. You do not need to keep the pH so low, but up to you. I add acid twice a week. That keeps the pH between 7.5 and 8 and TA around 80.

 

[JoyfulNoise]

You can use CO2 to control pH but you’re likely going to use a lot of it given the high temperatures here. Also, if you adjust alkalinity with muriatic acid, you’re going to need to discontinue using CO2 for a brief time as the two together will substantially drop the pH and could cause plaster etching.

I’m sure you’ll be able to find a routine that works for you but I think you’ll find the cost of using CO2 in addition to acid will make your pool care more expensive than it needs to be.

Have you tried just lowering your TA to 50ppm and then keeping your pH in the 7.6 to 7.9 range? That often is enough to space out MA additions to a reasonable amount of time. Borates help too in our climate. I only need to add acid every 10-14 days using low TA and higher pH.

 

[nofears]

I am not there all the time so I need something to help stabilize pH since it's the most impactful factor in LSI. I agree CO2 will need to be shut off during times of adding MA to lower alk. Appreciate all the response!

Oh and I tried 50ppm borates and it couldn't compete with my SWG...

 

[JoyfulNoise]

I am not there all the time so I need something to help stabilize pH since it's the most impactful factor in LSI. I agree CO2 will need to be shut off during times of adding MA to lower alk. Appreciate all the response!

Oh and I tried 50ppm borates and it couldn't compete with my SWG...

What does your fill water test at for pH/TA/CH?

My guess is your low pool volume, high heat and hard fill water combine to drive the pH up. SWG’s do aerate the water a small amount and their chlorine generation does raise pH temporarily but the pH rise from the SWG will mostly go away since chlorine sanitation and oxidation reactions are acidic in nature. Your SWG is also rated at nearly 8X your pool volume so that will impact it as well. The alkalinity added from your fill water is going to be the biggest contributor to pH and so anything you can do to stop the water from evaporating will help greatly to control pH.

 

[nofears]

CO2 system is online and has so far kept pH around 7.5...when it typically goes about 8 within 2 days. I am still making minor adjustments to CO2 flow rate to get it dialed in.

 

[silverfun]

CO2 system is online and has so far kept pH around 7.5...when it typically goes about 8 within 2 days. I am still making minor adjustments to CO2 flow rate to get it dialed in.
View attachment 499873

How has your system worked? I have a 10k pool in Florida and I hate handling acid, afraid of the fumes so I hold my breath every time I add to the pool. We have air gas locally that could refill tanks in neighborhood. Wanted to see how your system has been performing.