Stenner liquid chlorine pump - How to choose and install

Regnar

Active member
Oct 30, 2016
40
Oldsmar/FL
The black plastic nuts - how long are they lasting you in FL?

Steve they lasted about a year in direct sunlight. The clear tube only lasted a year too but it was covered by some white split loom to match the exterior. Just installed black tubing and new nuts with PVC cover. I will snap a photo when it stops raining.
 

Teald024

TFP Guide
Probably better for the pump and its associated parts and tubes, too, if long-term chlorine exposure has an impact. I'm going to switch to 14% MA for my acid pumper, down from 31%, for that reason.
The only part of the Stenner pump in contact with chlorine or acid is the inside of the tubing. Everything else is just exposed to the atmosphere and elements. Chlorine or acid strength really doesn’t have any effect.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,866
Tucson, AZ
Nice write up.

I don’t think the winter time running is much of an advantage. Once my pool water temp drops below 65F and starts to get too cold to run the SWG (ColdCutOff temp is 56F), my FC demand is insignificant. Last winter (Dec-Mar) I added approximately 80oz (less than a gallon) of 10% LC for the entire 4 months. My pump run times were also about 2 hours/day. So there really would be no advantage over the winter.

Also, two summers ago I ran a season long experiment of low FC/CYA ratio, ~3% all summer long. That translated to 4 hours of pump runtime (SWG at 40%) with the pump speed around 1600RPM (~350W or so). Pool stayed clean and clear all summer. So again, the power draw differences can be easily minimized.

Don’t get me wrong, liquid injection is fine. But there’s really very little difference in either setup. The economics work out the same - you will spend just as much money on bleach/LC as you would in front costs for an SWG over the typical lifespan of the unit. It really comes down to what one wants to do. Personally, I like the feel of my saltwater pool and I like not ever having to worry about which store has the lowest priced LC....all the chlorine I need is right there in water waiting to be turned into hypochlorous acid/hypochlorite.....
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
4,409
Central California
The only part of the Stenner pump in contact with chlorine or acid is the inside of the tubing. Everything else is just exposed to the atmosphere and elements. Chlorine or acid strength really doesn’t have any effect.
The pump's tubing (sorry, what is that part called?), and the tubing running to and from the pump, the injector and duckbill, etc... Pentair recommends regular replacement and/or monitoring of the entire chain, which I presumed was because of the potential for wear/failure due to exposure to MA. No? Or is it just the tube in the pump to worry about, due to movement?
 

Teald024

TFP Guide
Why is Pentair involved??

The Stenner pump is a peristaltic pump. It works by using rollers to pinch the tubing between rollers and the wall. As the rollers move around it repeatedly squeezes the tube and pushed the liquid through the tube. Like how you get that last drop out of a toothpaste tube. The moving parts technically never touch the liquid. The tube is subject to cracking over time so Stenner recommends replacing it yearly so that the risk of failure is reduced. The material of the tube inside the pump mechanism is selected to resist chemical attack from the chlorine and acid (or whatever the pumping liquid is). Stenner has a reference chart for the various tubes available that lists chemical resistance. Typical tube material for pool users is Stanoprene.
The duckbill is subject to clogging by any salt crystals and it is a good idea to check/clean it yearly. The hard plastic tubing running from tank to pump and then from pump to the plumbing is not immune to issues, but has a very low failure rate, similar to that of pvc piping.

how
 

Steve_in_C

Bronze Supporter
Jul 6, 2017
344
Kinston, NC
Nice write up.

I don’t think the winter time running is much of an advantage. Once my pool water temp drops below 65F and starts to get too cold to run the SWG (ColdCutOff temp is 56F), my FC demand is insignificant. Last winter (Dec-Mar) I added approximately 80oz (less than a gallon) of 10% LC for the entire 4 months. My pump run times were also about 2 hours/day. So there really would be no advantage over the winter.

Also, two summers ago I ran a season long experiment of low FC/CYA ratio, ~3% all summer long. That translated to 4 hours of pump runtime (SWG at 40%) with the pump speed around 1600RPM (~350W or so). Pool stayed clean and clear all summer. So again, the power draw differences can be easily minimized.

Don’t get me wrong, liquid injection is fine. But there’s really very little difference in either setup. The economics work out the same - you will spend just as much money on bleach/LC as you would in front costs for an SWG over the typical lifespan of the unit. It really comes down to what one wants to do. Personally, I like the feel of my saltwater pool and I like not ever having to worry about which store has the lowest priced LC....all the chlorine I need is right there in water waiting to be turned into hypochlorous acid/hypochlorite.....

I mean for the write up to be informative and do not mean to be biased. A SWG is absolutely worth doing rather than hauling bleach. My pool manufacturer absolutely recommends against a SWG and I don't have one due to concerns over corrosion. My pool is made from thick aluminum interlocking panels. I don't want to risk corrosion.

In terms of low temperature use, it's hard for me to judge that one. I haven't had a pool long enough to know how often it's needed. I did run my chlorine pump in March 2018 when my water temp hit 62 degrees. But after a week the temps dipped down again and I cut it off. I could have easily just shocked it manually and probably ridden out the heatwave. The daily dosing of chlorine back in March was a benefit to me. When I checked the CYA, it was 0. It was consumed by microbes over the winter. I thought I might do a bit more chlorinating over next winter.

In terms of electricity cost, those who have a VS pump don't have much to gain with a chlorine injection pump. For my setup with a single speed pump, the extra run time required for a SWG costs about the same as my chlorine bill. So each situation is different.

I shopped bleach prices in my area once. The higher concentration bleach is not cheap in my area. Walmart has the best price and once I settled on the 6% for $1.77/gallon, I have done no further shopping. I just order and pick up a large quantity all at once. i have 2 bleach hauls for an entire year of pool maintenance. i have a place to store it, so that is not an issue. Since it is 6% and has a long half life, I don't have to worry about the age of the bleach.

I'm looking to create a write up that outlays the issues with an injection system. Each person must weight the pros/cons for their own situation.

More feedback to hone the write up is appreciated.
 

Teald024

TFP Guide
My tube broke first this spring, about a week after opening. Since the water was cold and I wasn’t using much run time, 5 mins maybe, I didn’t notice it for a few days.
Stenner recommends changing out yearly. You can get more if you want to run it to failure. My tube lasted 2 seasons before failure with a 7 month use in a season. Your use may vary.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
4,409
Central California
Why is Pentair involved??

The Stenner pump is a peristaltic pump. It works by using rollers to pinch the tubing between rollers and the wall. As the rollers move around it repeatedly squeezes the tube and pushed the liquid through the tube. Like how you get that last drop out of a toothpaste tube. The moving parts technically never touch the liquid. The tube is subject to cracking over time so Stenner recommends replacing it yearly so that the risk of failure is reduced. The material of the tube inside the pump mechanism is selected to resist chemical attack from the chlorine and acid (or whatever the pumping liquid is). Stenner has a reference chart for the various tubes available that lists chemical resistance. Typical tube material for pool users is Stanoprene.
The duckbill is subject to clogging by any salt crystals and it is a good idea to check/clean it yearly. The hard plastic tubing running from tank to pump and then from pump to the plumbing is not immune to issues, but has a very low failure rate, similar to that of pvc piping.

how
Sorry, I made a leap there without clarifying. Pentair uses the exact same type of mechanisms throughout. I wouldn't be surprised to learn it is Stenner gear. The injector looks identical. And it's a peristaltic pump. My comments and questions were about that type of pump and its tubing, in general...

Thanks for the explanation, as it applies equally to Stenner and the IntellipH.
 

mswlogo

Well-known member
Jul 6, 2017
73
MA
I just installed one using the Pentair Tank (with pump on Tank).

Pentair Chlorine Tank with built in Pump

I expect to run it about 15-30 minutes a day which will put between 0.5 and 1.0 gallons of 12.5% in.

Tank is pretty small (4 gallons), but there are pro's to that in that if something goes wrong it's a smaller scale problem. Takes less room in my shed too.

I can remotely enable or disable the schedule from a SmartThings Hub paired to a Intermatic PE653 Controller. But it requires PE953 (Local Remote) to adjust the schedule.

With Galvanized walls and aluminum fittings I decided to stay away from SWG. If I installed a new pool with plastic walls and brass fittings I might go with SWG.
Since the SWG needs regular Acid, it has all the down sides of having a Chlorine Tank (IMHO) on top of the downsides of running a SWG.

I didn't know the Stenner Tube needed to be replaced annually. Ugh.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,866
Tucson, AZ
....
Since the SWG needs regular Acid, it has all the down sides of having a Chlorine Tank (IMHO) on top of the downsides of running a SWG.
This is an often quoted misconception about SWG’s that is false. SWG’s are pH neutral and bleach injection is only slightly pH increasing (due to the excess caustic in all chlorinating liquids). As such, SWG pools do not require acid per se. What typically happens is pool owners get used to using solid chlorine sources which are generally acidic in nature (dichlor and trichlor are acidic) and so their pools are dosed with both chlorine AND a source of acid all the time. When they switch to an SWG or liquid chlorine dosing, they suddenly are no longer adding a source of acid all the time and they need muriatic acid to lower pH. They then falsely attribute the rise in pH to the installation of the SWG. There are plenty of examples of people that install SWGs and never need to add acid to control pH. It all depends on their source water alkalinity and the presence of aeration sources. SWGs contribute almost nothing to pH rise. One can easily prove this by simply covering a pool and running the SWG. Once evaporation is stopped and aeration is reduced, pH rise slows dramatically.

As is often said on this site and needs constant repetition - pH rise in swimming pool water is entirely dominated by CO2 outgassing.
 

garyduse

LifeTime Supporter
May 30, 2008
23
Seattle area
I'm in the process of doing some replumbing to improve accessibility and replace some troublesome ball valves. My pool is in-ground and the equipment is all below water level (no pump priming issues). I have a DIY Stenner chlorine injection system, plumbed into the return line, which has been working well for 3+ years. Currently, I have a check valve on the return line between the pool heater and the chlorine injection fitting. The Stenner pump is on its own timer and wired such that it cannot operate unless the main circulation pump is running. The circulation pump is always set to run for several minutes after the chlorine pumping cycle has shut off.
So, with this setup in mind, is there any real need for the return line check valve? I can understand the need for it with an in-line tablet chlorinator, but can't see how, with the Stenner system, there is any way for super-chlorinated water to backflow into the heater.
Am I correct or am I missing something?
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
4,409
Central California
This is an often quoted misconception about SWG’s that is false. SWG’s are pH neutral and bleach injection is only slightly pH increasing (due to the excess caustic in all chlorinating liquids). As such, SWG pools do not require acid per se. What typically happens is pool owners get used to using solid chlorine sources which are generally acidic in nature (dichlor and trichlor are acidic) and so their pools are dosed with both chlorine AND a source of acid all the time. When they switch to an SWG or liquid chlorine dosing, they suddenly are no longer adding a source of acid all the time and they need muriatic acid to lower pH. They then falsely attribute the rise in pH to the installation of the SWG. There are plenty of examples of people that install SWGs and never need to add acid to control pH. It all depends on their source water alkalinity and the presence of aeration sources. SWGs contribute almost nothing to pH rise. One can easily prove this by simply covering a pool and running the SWG. Once evaporation is stopped and aeration is reduced, pH rise slows dramatically.

As is often said on this site and needs constant repetition - pH rise in swimming pool water is entirely dominated by CO2 outgassing.
I have heard multiple (anecdotal) explanations why an SWG increases pH (bubbles/aeration, chemical, etc). And I've read other posts, perhaps where you explained this elsewhere Matt, that SWGs do not contribute to pH rise. But in my own pool, I witness this phenomenon first hand, whatever the cause. I have a model TFP pool. I've added water, CYA, "liquid" chlorine, salt and MA. Absolutely nothing else, since the pool was resurfaced with pebble. There are no water features. I've never used solid chlorine sources of any kind. I experienced the expected pH rise from the new surface, while I ran the pool as non-swg, well tested and documented with my Taylor 2006 and the Pool Math app. Pretty constant, repeatable pH rise. I added salt and more CYA and turned on the SWG this spring and experience a very marked increase in pH rise, also well tested and documented. So much so that I had to dose with MA everyday, just to maintain high 7s. It was not a small amount of increase in pH rise.

I do have a fair amount of wind, moving the surface water. My returns point slightly down and only agitate the surface very slightly. I have high TA fill water. And I started the SWG in spring, so evaporation rate was on the rise. Based on your CO2 outgassing comment, all those could contribute to my pH rise. But that doesn't explain why all those conditions existed both before and after I turned on the SWG, and the increase in the rate of pH rise happened instantly after turning it on. Not gradually as you would expect if one of the aforementioned conditions were the cause (for example, the evaporation rate didn't suddenly, coincidentally increase the day I turned on the SWG).

So while I don't doubt the validity of the science of your comments, Matt, I have a pool that contradicts what you're telling us. Not to mention there seems to be a large contingent of TFPers that also experience this same pH rise with their SWGs. If it's not my SWG, then what is it?

Sorry to hijack this thread, but Matt is saying (I think) that a chlorine injection system will contribute to pH rise more than an SWG (his second sentence), and I'm finding that hard to believe. I can somewhat rationalize bringing this up in this thread, as it pertains to the pros and cons of SWG vs Stenner.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,866
Tucson, AZ
Dirk,

You have highly alkaline fill water and your pool is uncovered. Throw a bubble cover on your pool and I guarantee you will see your acid demand all but stop. Seasonal variation of pH demand is to be expected as outgassing increases with temperature, just like warm soda will bubble over and froth more than a cold soda. You don’t need physical movement of the water to outgas CO2, it happens all on its own. Aeration simply speeds up the process. If your SWG is too close to the pool you can get what’s called a short-pipe effect where both chlorine gas and hydrogen gas leave the pool; that would cause a strong rise in pH. But most SWG installations will not suffer a short-pipe problem as there is typically ample run in the return line to let the chlorine gas dissolve.

The pH rise is coincidental to the summer swim season and not the SWG. Unless you’re running your SWG at 100% output 24/7 then the amount of aeration is not that significant.

Liquid chlorine is only slightly alkaline when used in a pool. It takes SLAM type additions of bleach (many gallons) to have an impact on pH rise. Normal daily additions of 3ppm FC is not going to noticeably raise pH.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
4,409
Central California
OP, back to the topic, if I'm understanding Matt correctly, pH rise is a relative non-issue when deciding between pump or SWG. It's academic to me, because my rise is real, and the cause doesn't concern me much. I have to deal with pH rise, as many pool owners do. I decided to solve it with an acid pump, and now my pH is rock solid steady. Hopefully you'll see the same with FC with your pump...
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,866
Tucson, AZ
Chem Geek's post

Chemistry behind chlorine salt water generators

I add liquid chlorine, have borates in my pool, and a TA of about 70. My pH stays relatively stable at 7.6. I have added small amounts of acid 3 times in 2018. It's not often. No alkaline water here. My fill water has a pH of 5.2 (well water).
Your well water is quite acidic but not out of the norm for an east coast aquifer. Even with an SWG, you’d likely need the same frequency of acid additions. Your low TA, acidic fill water and borates are enough to stabilize the pH.

By comparison, my municipal water has a pH of 7.7-7.8, TA of 120ppm and a CH of 180-200ppm. The addition of my fill water and outgassing of CO2 drives my pH rise and I typically need to add acid every 7–10 days.
 

1Sammy

In The Industry
Jul 20, 2017
205
Windsor, Ontario. Canada
I'm in the process of doing some replumbing to improve accessibility and replace some troublesome ball valves. My pool is in-ground and the equipment is all below water level (no pump priming issues). I have a DIY Stenner chlorine injection system, plumbed into the return line, which has been working well for 3+ years. Currently, I have a check valve on the return line between the pool heater and the chlorine injection fitting. The Stenner pump is on its own timer and wired such that it cannot operate unless the main circulation pump is running. The circulation pump is always set to run for several minutes after the chlorine pumping cycle has shut off.
So, with this setup in mind, is there any real need for the return line check valve? I can understand the need for it with an in-line tablet chlorinator, but can't see how, with the Stenner system, there is any way for super-chlorinated water to backflow into the heater.
Am I correct or am I missing something?
Not sure i read your post correctly, sorry. The duckbill ( check valve) inside the stenner injector is for sure a must in my mind as if that 1/4" or in some cases a 3/8" ever breaks or a fitting comes off, you will pump your pool water out. The way i read your post you have this, great. Leave it. Also a good backup for if / when the pump tube breaks and if you are plumbed back from the stenner head to your tank it will not overflow with pool water.
I think you now have a check valve after your heater and before the injection point, not needed.
I would have the main pump running longer then a few minutes after the stenner shuts down though.
Question please if i may. You say this, "The Stenner pump is on its own timer and wired such that it cannot operate unless the main circulation pump is running." How have you done this ? I have been going over a few options in my mind to do this to my set up but have not found the answer yet.
 

mswlogo

Well-known member
Jul 6, 2017
73
MA
Not sure i read your post correctly, sorry. The duckbill ( check valve) inside the stenner injector is for sure a must in my mind as if that 1/4" or in some cases a 3/8" ever breaks or a fitting comes off, you will pump your pool water out. The way i read your post you have this, great. Leave it. Also a good backup for if / when the pump tube breaks and if you are plumbed back from the stenner head to your tank it will not overflow with pool water.
I think you now have a check valve after your heater and before the injection point, not needed.
I would have the main pump running longer then a few minutes after the stenner shuts down though.
Question please if i may. You say this, "The Stenner pump is on its own timer and wired such that it cannot operate unless the main circulation pump is running." How have you done this ? I have been going over a few options in my mind to do this to my set up but have not found the answer yet.
In my case the Intermatic PE653 takes care of it. I set it up as a "Pool Cleaner Boost" circuit which has the option to require the pump be running when running the Stenner Pump Circuit. I expect to run it around 20min a day.

If you run 120V pump (many folks have 220V) make the Pump power (the "Hot") the "source" power in series with the Timer Switch.

If it's a 220V pump you should not really tap 120V off one leg because there is no corresponding neutral for 120V. In this case you should add a 220V Relay and have that be in series with the timer switch (with it's own 120V source).
 

Steve_in_C

Bronze Supporter
Jul 6, 2017
344
Kinston, NC
I did the same thing. The outlet running my Stenner is only "hot" when my main pump timer is on. You can't even turn on my Stenner pump unless the main pump timeclock circuit is energized. In order to do this you MUST have a timer on your Stenner that will store settings for a long time without power as it may go 23 hours per day without any power to that outlet and timer. My pump is wired 120V and I tapped the Stenner outlet in parallel with the pump outlet.

For 240V, like mswlogo said, you can energize the coil of a 240V relay with the pump timeclock. The relay or contactor can have it's own 120v source running through the contacts to power the outlet. The coil would be wired in parallel with the pump outlet. This one is $10 https://www.amazon.com/Packard-C230C-Pole-Contactor-Volt/dp/B004YW5CWQ/ref=sr_1_3?ie=UTF8&qid=1532579041&sr=8-3&keywords=240v+coil+contactor you'd have to mount it in a box between your pump timeclock and your Stenner outlet. You can run the neutral and ground straight through and just use one pole to break your hot leg. This would work with a GFCI circuit / breaker as well.

Like 1Sammy, I run the pool pump longer that the Stenner. I cut my pump on 5 minutes before the Stenner cuts on and run it at least 5 minutes after the Stenner cuts off. I don't want any high chlorine concentration close to my heater/filter/pump setup.