Poolsmith CO2 injection for pH control

[slidingsky]

I just threw a co2 tank on my salt pool. I eat 1 gal of 15% acid a week. I think its pebbletec plus all my trees, i have to run my swg pretty high to keep my fc up which pushed my ph up. Acid is going up in price and i want a project.
So far i got 2x 20lb alm co2 tanks on facebook for 140 for the pair. The regulator has a 110v solenoid and flow control, which was 40bux. Airgas in vegas charges $30 to fill a 20lb tank and $35 to fill a 50lb. I already built a stenner injector with a dedicated 110v outlet tied to an aux and flow switch for safety. It worked well, but yeah my TA takes a Crud in summer. I guess ill probably keep both for options for now. The stenner with the 15gal tank was not cheap, plus i did all the hook up myself. Electrical was not bad, but more than someone with no knowledge of relays could do.

 

[slidingsky]

Here the el cheapo regulator. It has like no outlet pressure so i had to remove the stenner duckbill check at the injector port. So far its working for pretty cheap.

 

[zolakk]

That's pretty cool, so if I understand things right you're basically using one of these: CO2 regulator with solenoid valve plus one of these stenner injection check valves paired with one of these tees on the pool side (ignoring the safety flow switch stuff)? Price of tanks aside, that's a lot more doable than the poolsmith system since I already have an automation system I can hook a relay to for control. For tank storage, are you just keeping your tank outside? I'm in Vegas too and I wonder how it would hold up in the heat

 

[garyschuetz]

When I first turned the system on, gas was not flowing through the meter, even though I verified that gas was being supplied to the controller input. Poolsmith is a small company, and I was able to immediately get in touch with the owner. We walked through some basic diagnostics (just to make sure I hadn't made some mistake in installation), and he concluded that the problem was inside the controller and agreed to send me a new unit, which he shipped out later that same day.

A couple of hours later when I had some time, I decided to pop the front cover off to see if there was anything obviously wrong. Sure enough, the short tube that connects the flow meter to the relay had gotten crimped, probably during final assembly. The internal tubing is identical to the external tubing, so I was able to remove the damaged tubing and replace with a short length cut from the external tubing that is part of the kit, and voila it worked.

I have initially set the flow rate and timer settings to the values recommended for my size pool, and we'll see what happens. I will periodically add new posts with my observations on performance.

I came across your post and really appreciate the detail and pics showing your system. I'm venturing into the CO2 injection method for my pool for pretty much the same reasons you are. I hadn't thought of injecting into the pump strainer until seeing your pic and it occurred to me that the guys at Poolsmith might be considering the low pressure point for injecting as well as the mixing benefits of the pump impeller prior to flowing the infused gas back to the pool. Pretty smart in my opinion. I have an 'in-floor' cleaning system that I expect will also optimize distribution for balancing. I have a 16K gallon in-ground pool in Phoenix AZ that I dose daily in the summer here (when the pool is above 90 degrees) with about 2 cups of 10% liquid CL and to keep my pH (in the high range of around 7.7) is usually have to add about a cup of the 30% MA every day or two. I watch the TA (which I've been keeping in the low range of around 60) slowly drops over several weeks and I have to throw in a few pounds of A&H powder. I was wondering what to expect for CO2 flow rate and injection durations for my setup and curious if your experience can guide me.

 

[cptkirk]

You will have to experiment on the flow rates and injection time settings. The system comes with some recommendations based on pool size, but that is really just a starting point.

 

[JoyfulNoise]

I came across your post and really appreciate the detail and pics showing your system. I'm venturing into the CO2 injection method for my pool for pretty much the same reasons you are. I hadn't thought of injecting into the pump strainer until seeing your pic and it occurred to me that the guys at Poolsmith might be considering the low pressure point for injecting as well as the mixing benefits of the pump impeller prior to flowing the infused gas back to the pool. Pretty smart in my opinion. I have an 'in-floor' cleaning system that I expect will also optimize distribution for balancing. I have a 16K gallon in-ground pool in Phoenix AZ that I dose daily in the summer here (when the pool is above 90 degrees) with about 2 cups of 10% liquid CL and to keep my pH (in the high range of around 7.7) is usually have to add about a cup of the 30% MA every day or two. I watch the TA (which I've been keeping in the low range of around 60) slowly drops over several weeks and I have to throw in a few pounds of A&H powder. I was wondering what to expect for CO2 flow rate and injection durations for my setup and curious if your experience can guide me.

In AZ it’s going to be challenging to get CO2 to work economically. Water here has high TA (generally above 100ppm) and CO2 works best when the TA of water is low. Your pH rise is entirely dominated by the fill water you add from evaporation of the pool water. While CO2 will lower pH, you’re going to need to use acid anyway to reduce TA as that is what causes rapid pH rise. You’ll go through a lot more CO2 than most other parts of the country where TA is low.

You can certainly give it a try but I think you’ll find yourself having to use a lot of CO2 in the summer months.