DIY CO2 Injection for pH Control (not CircuPool or Poolsmith)

[tfpdubld]

Hello TFP ! Assuming the exploration around why pH is rising and debate between automated CO2 vs. MA to lower pH has ended with CO2 being selected, I wanted to create a WIP DIY set of materials needed since I couldn't find one that existed already. Lots of great threads on those first two topics by searching "co2 injection" and "acid pump options". This is intended for folks set on CO2 and potentially considering the much higher priced CircuPool or Poolsmith systems but want to dose on a simple Jandy schedule and test kit results.

Here's the system I'm building after being inspired by this thread setting up commercial/DIY CO2 pH automation (thx @cptkirk @JoyfulNoise, @slidingsky, @zolakk!) and this thread setting up DIY MA pH automation with Jandy automation (thx @santacruzpool!).

Materials

1. 2 x 20lb aluminum CO2 tanks (1 spare, 1 connected) - $20 exchange in NorCal @ garden supply stores
2. 20lb tank mount - in case you live in an *extremely* space constrained environment (me) or for security
3. CO2 regulator w/ flowmeter (remove the 110v OEM solenoid)
4. 1/4" 12V solenoid w/ push fitting adapter
5. 30W 240V -> 12V transformer (power chained to filter power relay) & 20AWG low voltage wire
6. 1/4" air line is included with the regulator, but if you need extra...
7. 1/2" injection check valve

Automation Setup

1. transformer connected to an available relay (powered by pump relay, ideally) & that relay to an available aux
2. aux set to max runtime of x minutes (as a precaution)
3. schedule triggers aux y minutes per day during pump run time (based on time + flow + need)

For folks tagged or anyone with a DIY CO2 system, any parts or materials I'm missing? All thoughts and feedback welcome...but go easy it's my first post! I'll make sure to update based on input, especially links to better priced or higher quality equipment.

Updates:
8/2 added link to tanks and tank mount
8/8 updated push fitting and check valve links, added photos

 

[Dirk]

OK, I know this is the exact opposite of what you want to hear, but I'd be remiss if I didn't share. I'm in Central CA and my fill water is high in TA. This puts a lot of pressure on my pH, which is constantly on the rise. I use Muriatic Acid (MA) to control the pH, which also brings down the TA in the pool, which lessens the pressure on my pH. Sort of a "two-fer" solution.

If I remember correctly a thread I just read, CO2 will bring down your pH, but not your TA. (I think @mknauss will correct me if I'm remembering that wrong.) Which means you'll be fighting the pH with CO2 but not doing anything about TA. You might actually have to use MA anyway, to control the TA.

And of course, depending on where you live, the acid is generally very available, where CO2 might be harder to come by.

I've automated this pH/TA control solution, and so dispensing MA is really no bother at all.

So if your fill source is high in TA (have you tested it?), I just wanted to make sure you are aware of an alternative that might better serve you. Apologies if you've already figured this out and it doesn't apply to your pool.

Either way, welcome to TFP!

 

[tfpdubld]

@Dirk thanks for the warm welcome and for pointing out an important aspect of using CO2! i'm up in NorCal and with fill water TA 50... you're spot on that CO2 won't drop TA and folks should plan to keep using MA w/ aeration to keep TA at target level. i'm good with handling MA and agree it's no problem...

 

[tfpdubld]

Some photos of everything installed...

 

[Skurzban]

Hello TFP ! Assuming the exploration around why pH is rising and debate between automated CO2 vs. MA to lower pH has ended with CO2 being selected, I wanted to create a WIP DIY set of materials needed since I couldn't find one that existed already. Lots of great threads on those first two topics by searching "co2 injection" and "acid pump options". This is intended for folks set on CO2 and potentially considering the much higher priced CircuPool or Poolsmith systems but want to dose on a simple Jandy schedule and test kit results.

Here's the system I'm building after being inspired by this thread setting up commercial/DIY CO2 pH automation (thx @cptkirk @JoyfulNoise, @slidingsky, @zolakk!) and this thread setting up DIY MA pH automation with Jandy automation (thx @santacruzpool!).

Materials

1. 2 x 20lb aluminum CO2 tanks (1 spare, 1 connected) - $20 exchange in NorCal @ garden supply stores
2. 20lb tank mount - in case you live in an *extremely* space constrained environment (me) or for security
3. CO2 regulator w/ flowmeter (remove the 110v OEM solenoid)
4. 1/4" 12V solenoid w/ push fitting adapter
5. 30W 240V -> 12V transformer (power chained to filter power relay) & 20AWG low voltage wire
6. 1/4" air line is included with the regulator, but if you need extra...
7. 1/2" injection check valve

Automation Setup

1. transformer connected to an available relay (powered by pump relay, ideally) & that relay to an available aux
2. aux set to max runtime of x minutes (as a precaution)
3. schedule triggers aux y minutes per day during pump run time (based on time + flow + need)

For folks tagged or anyone with a DIY CO2 system, any parts or materials I'm missing? All thoughts and feedback welcome...but go easy it's my first post! I'll make sure to update based on input, especially links to better priced or higher quality equipment.

Updates:
8/2 added link to tanks and tank mount
8/8 updated push fitting and check valve links, added photos

A few questions: 1) Are you piping the CO2 into the pool pump through the drain plugs like Circupool and Poolsmith? 2) If so, I noticed Circupool and Poolsmith systems have a second plumbing line for pressure and Circupool says their system cannot operate without the pressure line. How do you deal with this (again, assuming you are piping it into the pump)? 3) I am guessing you want to low voltage to tie in with your existing timer. I have a smart outlet, so I would just use that. Any other reason you switched it from 110v to 12v?

 

[robj01]

A few questions: 1) Are you piping the CO2 into the pool pump through the drain plugs like Circupool and Poolsmith? 2) If so, I noticed Circupool and Poolsmith systems have a second plumbing line for pressure and Circupool says their system cannot operate without the pressure line. How do you deal with this (again, assuming you are piping it into the pump)? 3) I am guessing you want to low voltage to tie in with your existing timer. I have a smart outlet, so I would just use that. Any other reason you switched it from 110v to 12v?

Thank you for sharing this project in such great detail. Additional to Skurzban's questions, I am interested to know what your experience has been with the finished system.