Stenner Acid Injector Placement

[Davwil]

I'm in the process of rigging up a Stenner pump for pH. I've read dozens of past posts on where the best place to put the injector (and dilution rates, check valves, etc.). Some recommend putting the injector before the SWG and some say definitely after it. My options are limited due to the fact that the plumbing doesn't allow for inserting an 2"-1/4-2" PVC tee. I would have to totally re-plumb everything and buy more fittings for the SWG, more Jandy 3-way cutoff valves, etc. , which I rather not do at this point. I'll have to drill and tap a hole, which is fine. I can do that. Based on my layout, I have three viable options:
1) I can place the injector just past one of the SWG (about 2" down the line after the SWG). Is that too close to the chlorine being made?
2) I've read where the injector can be placed in the drain of the pool pump which would route the acid directly into one of the cartridge filter and then through the SWG. I have the Pentair Intelliflo VSF pumps. And they run 24/7 just at different speeds.
3) I also have room on the PVC pipe going from the pump to the filter intake.

Any thoughts or suggestions would be welcome. Thank you.

 

[PoolStored]

The injection point is recommended before the swcg because of the belief that the acid will help keep the cell cleaner and thus require less manual cleaning.

 

[Davwil]

The injection point is recommended before the swcg because of the belief that the acid will help keep the cell cleaner and thus require less manual cleaning.

Thank you. I wasn't sure. I read one post where there was a concern that injecting acid before the swcgwould remove the titanium coating from the swcg and shorten its lifespan. Putting it before the swag will certainly makes things easier. Do you know if it would cause a problem putting the injector on the intake line going into the cartridge filter housing? That would be my easiest option.

 

[PoolStored]

Some industry reference might help. In the Pentair manual for their IntelliPH system, the installation instructions have the acid injection clamp shown as being 12" BEFORE the SWCG. There is some debate on these threads as to what is the best arrangement. The SWCG environment can be very alkaline due to the chlorine generation process and so, having acid injected before the cell can help reduce the pH inside it and help prevent scaling.

Do you know if it would cause a problem putting the injector on the intake line going into the cartridge filter housing? That would be my easiest option.

What dilution of MA are you using? The largest concern would be low pH.

Here is a good thread on injecting upstream and dilution.

Homemade Acid OR Chlorine Injection System

Having a plaster pool with a SWG and fill water with high PH and TA has meant a constant battle with rising PH. I have tried the borax route with lowered TA but because of the high TA fill water, I haven't had much success in lowering my acid use. So I decided to look into acid injection...

www.troublefreepool.com

 

[Davwil]

Some industry reference might help. In the Pentair manual for their IntelliPH system, the installation instructions have the acid injection clamp shown as being 12" BEFORE the SWCG. There is some debate on these threads as to what is the best arrangement. The SWCG environment can be very alkaline due to the chlorine generation process and so, having acid injected before the cell can help reduce the pH inside it and help prevent scaling.


What dilution of MA are you using? The largest concern would be low pH.

Here is a good thread on injecting upstream and dilution.

Homemade Acid OR Chlorine Injection System

Having a plaster pool with a SWG and fill water with high PH and TA has meant a constant battle with rising PH. I have tried the borax route with lowered TA but because of the high TA fill water, I haven't had much success in lowering my acid use. So I decided to look into acid injection...

www.troublefreepool.com

Thanks that's a great link...helpful. It raised a few more questions/concerns.

I haven't decided what, if any dilution, I should use for the acid. Locally I can get either the 15 or 30%. The 30% is less expensive. And, I have a 35 gallon tank so I don't think dilution would be an issue. At this point, I still haven't figured out exactly how much acid I need to add weekly/daily. This is the first season I've had the pool and I have ordered boric acid and plan to add that soon, which might have an effect.

My equipment sits about 8 feet below the pool water line. I was first worried about back flow into the Stenner tank, but others using Stenner pumps said that's not an issue since the tubing is compressed by the pump rollers and prevents this.

When the pool was built, a drain was installed that would let excess water from heavy rain/s drain from the pool. It consists of a 1" PVC pipe that sits at the top of the pool tile line. If I could get the proper length of tubing (30 to 40') that can handle acid, I could run the tubing from the equipment room through that PVC and have it dump below the water line directly into the pool. This might eliminate all of the other factors. I might need to put a check valve on the tubing so it doesn't siphon the pool water back into the tank (again, with a Stenner pump that might not be a problem, but it's "cheap insurance"). At this point this seems like my best/easiest option. The article you linked made me start thinking of other ways to just dump the acid directly into the pool and bypassing the pumps, filters, etc.

 

[Davwil]

What I need to do now is find some UV proof, 1/4" tubing that can handle acid.