Stenner Pump for acid

[Jaimslaw]

Moderator note - moved from here: New Build - Stenner Pump?


I've read the other excellent posts about Stenner injection set ups - although most seemed to be for Chlorine vs acid. Still just a tad confused, mostly whether to go adjustable or go with a fixed/timer set up.

My acid demand for my 13K pool (high PH creep due to SWG + high areation via two spillovers) is approx 2 quarts every 4-5 days - maybe more - that's using the Leslie acid, and not the Home Depot watered down stuff. Even tho I have a nearby GFCI, I'd like to avoid the timer set up and hard wire the Stenner into my Aqua Logic PS4 panel so that it runs only when the pump is on. This would seem to eliminate any safety issues in the event of a timer malfunction or power outage that might have the Stenner runing when the pool pump is not (or is it that serious a concern?). So, does the foregoing not make the set up of [adjustable + sync with pool pump] the preferred way to go (vs if chlorine is the chemical?).

Also, am I correct that my acid injection amount per day would be considerably less than it would be if I were dispensing chlorine, correct? So I assume the Stenner 45MHP2 3GPD would be a good fit. (If I am not mixing up my Steener model numbers) with the 15 gal. and the 3/8" tubing. BTW< some sites selling Stenner products offer two kinds of tubing material; one which is acid compatible and one that is not. Other sites don't differentiate and so I guess I will have to call the store and ask them about the tubing material being sold as their stock 3/8" tubing.

I plan on a 2:1 ratio to perhaps make for a longer refill intervals, so I also assume this factors in to not needing a high rated Stenner model.

One last follow up question: why is the injection point before and not after the SWG???

Thanks for any input (and those prior posts about this subject).

 

[Bama Rambler]

You can get by with the smallest fixed rate pump they make. I recommend the fixed rate over the adjustable rate pump because of the lesser amount of regular maintenance required. You also don't need the 3/8" tubing. I would recommend the black uv stable tubing.

You'll need a timer that will provide at least minute resolution.

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.

 

[Jaimslaw]

I guess the amount of acid infused is considerably less than would be the case with chlorine infusion, which I assume accounts for the smallest rated pump recommendation. And acid before SWG to help the cell - that does make sense.

I'm all for less maintenance via the fixed rate pump - I guess it will be a trial by error exercise dialing in the timer to obtain optimal PH, whether its fixed or adjustable. I actually look forward to that exercise.

I recall a thread that recommended a digital timer and will hunt that up; I believe it was rated for exterior use and would be hardy enough to avoid any glitches due to exposure. The reason I am still a little hesitant to go with the fixed rate pump + timer is that I have a lot of digital timer connected devices at my house - irrigation, exterior lighting - a lot of my interior lighting; I do have occasional issues with those getting out of sync becuz of power being turned off or just plain glitchiness of timers. So I do wonder a little about the Stenner getting out of sync with the pool pump.

If the pump is off and the Stenner is on, I'm clueless as to the potential consequences. Can you give me an idea of what would happen? That is, does the pump simply introduce the acid into the short run of pipe and/or the SWG? Or is there resistance and an acid backup potential? If so, doesn't this just mean an overflow/backflow of the acid back into the container? My set up is on an exterior concrete pad so I/m not concerned about acid spillover causing any damage. But still...

I guess its up to me to weigh the two downsides: possible timer issue leading to adverse acid infusion scenario vs. downside of syncing an adjustable Stenner to my pool pump but dealing with the maintenance thing. I am leaning toward the latter option as less maintenance is always a preferred thing for me.

Thanks for you input. (And probably overthinking this).

 

[diverminh]

Jaimslaw - I am also in the process of doing an acid dosing system. I am using a combination of a timer and pH Controller to dose my acid. Tomorrow I will try to post some pictures to give you an idea of what I am doing.

Minh

 

[Jaimslaw]

Scratch my eyeballs with some pictures of your set up.

 

[diverminh]

Jaimslaw -

My apologies for not getting back earlier. Life has been a little hectic. The device I built below is not complete, and there are still room for improvement.

Basically, you will need to build the device below. Parts are also listed below. You will need some sort of dosing pump. I am using a Stenner 45MHP10. You will also need a controller. I found that the Milwaukee SMS122 or the Milwaukee MC122 will work. The MC122 has two calibration point, where as the SMS122 only has one calibration point. But since we don't have to be super precise, the SMS122 will probably work. What I do like about the SMS 122 is that is is configured to only dose when the pH is too high. The MC122 can be configured to either dose when pH is too high or pH is too low. My concern with the MC122 is that someone (me?) can accidentally turn on the switch to tell it to dose when pH is low - this it keeps on adding acid and create a potential disaster. The controllers are not waterproof so you will need to create some sort of housing to keep it dry. I bought my pH controller used for $40 from a aquarium person. If you buy it used, you may need a new pH probe.

I have the acid doser set up after the filter. Since I have a solar heater, my water drain when the pump turns off. As a result, I used a 2" coupler to create a little "well" so that even when the pump drains, the pH probe head remains wet. I wish I had enough room to put the acid dose in front of my SWCG, but I didn't have room without some major replumbing (which I am not ready to do at this point).

Having run this for a few days, I noticed a few things.
1) If I dose at the fastest rating, the acid dose too fast, but doesn't have time to registrar with the pH meter. So I have it set for pH 8.5. The acid dose, but since the acid has not mixed into the water and gone back to the probe, the pH is registered high. It keeps on dosing. Eventually too much acid is dosed resulting in pH of 8.2. When i get back from vacation, I am going to modify the plumbing to eliminate this problem. I just have to think about it a little more. I am also thinking about putting in a flow monitor so that the acid dosing turns off if the flow stops. Stay tune for more

Plumbing parts assuming you have 2" plumbing. Please adjust plumbing size as needed.

Pipe fitting parts:
2" PVC Cross (all slip fitting)
Small section of 2" pipe
2" (slip) to 1/2" (threaded) bushing - QTY 2
2" pipe coupler
Rola-Chem 550089 1/2" fitting for pH electrode (qty 2)
Electronic / pump parts:
pH Controller (I'm using the Milwaukee SMS 122)
Pump:
Stenner Pump 45MHP10
Container for acid:
Whatever works for you. Make sure that you have a container that is semi-air-tight. You don't want the acid fume. But you don't want it air tight either. I have a 1/16" hole drilled in my container to let air in and out, but not too much of the acid fume.

 

[Agent99]

I think you need to move your probe further away from the dosing point perhaps?

Cool set-up...love the PVC cross as you don't see many of them.

 

[diverminh]

Chris,

I think you are correct. The acid feed needs to be upstream from the probe. But I still want it close to the probe.This may cause the Stenner pump to cycle a lot, but I don't think that will be an issue at all. I am also thinking about adding in a flow sensor so that when the flow is off, the Stenner pump will not turn on. I have some testing to still do when I get back from vacation. Honestly - I am semi tempted to tear out all the plumbing and redo it. I am not crazy how the pool building plumb the equipment.

Minh

 

[diverminh]

So my pH swing widely in a very short period time. I am wondering if it might be due to the SWCG being before the pH probe. Unfortunately, I am gone for two weeks so won't be able to test out this theory until I get home. It's also possible that I bought a cheap pH probe, and that could be causing the problem.

 

[Jaimslaw]

Chris,

I am also thinking about adding in a flow sensor so that when the flow is off, the Stenner pump will not turn on.

Minh

I'm still searching the forum to better understand exactly what happens if the Steener pump does run without the pool pump, i.e., what happens with the acid being injected into a pipe that does not have moving water? Does it back up and spill over into the holding tank? Or will the acid harmlessly push its way into the section of pipe and sit there, to be flushed into the pool when the pump starts up again?

 

[bdavis466]

The biggest concern with the issue you describe is the potential for a very concentrated volume of water with very low pH make its way back to your heater and damage the copper. I'd recommend installing a check valve after the heater but before your acid injection point (if you don't already have one).