Stenner Pump Fail?

[GoGrabTheNet]

Today, upon inspection of my Stenner pump, model 45MPHP10 used for 10% chlorine injection, I noticed that the #2 tube has split. I also noticed that the Stenner check-valve (threaded to pool plumbing) was completely caked up with chlorine salts. This may be just due to the solution drying up since there was no flow. The pump has been installed and in operation since October 2016. Is this typical? Seems like the tube did not last long at all!

The pump is covered by the Stenner rubber/vinyl cover and also the rain hood. Sunlight exposure is thereby limited, but it could be better. Here in AZ, the sun is hot, and perhaps the temperatures and the sunlight made the tube stiff. However, even the brand new tube (included with a Stenner pump purchase) is stiff as well. It is a pretty thick-walled tube after all. However, the rest of the pump and assembly remains in great shape. The pump only runs 20 minutes a day in the morning when it's much cooler.

Just wanted to see what you guys think. Should the tube last longer? If not, then I must buy a box of them and keep them on hand! The Stenner automation is convenient, if it does not fail, but if tube replacement must proactively occur every 6 months, then it's NOT very cost-effective.

I should also note that I use the 10% chlorine solution from Lowes or Home Depot. I buy this because it's convenient for me, despite maybe not getting the best price per oz of chlorine. However, if it's known to be garbage (i.e. having too much salt, etc.), then I will discontinue using it and find another method, such as carboys from the pool store.

Thanks!

 

[Bama Rambler]

I usually change the tube once a year, but I haven't had one split even after several years. I'd say that you got a defective tube.

I'd replace it and I'm sure the next one will last much longer.

 

[RonsPlc]

I have changed my #2 tube yearly regardless of what it looks like... I have not had a problem with it.
and given that your pump is a 100psi pump, I would not be concerned with the buildup of salts...
I live in Alabama, not AZ... but on doing some reading, I chose NOT to put the rubber cover on my pump... (it would just trap heat in).
I need to buy another 2 tubes right now (or by the end of the season) to get me through the next 2 seasons.
I would not buy them in bulk, to ensure that they work the way they are intended... besides, they are cheap enough for what they do.

 

[GoGrabTheNet]

Thanks for the replies.

The tube could have been defective, or maybe I inadvertently twisted it while tightening the collars for the inlet/outlet tubes which could have led to a premature failure. I have since replaced the tube with the spare I got with the pump making sure I didn't twist it during installation.

Overall I chose to install the vinyl cover over the pump not to keep rain out (not much here in Phoenix, but when it does it pours!), but rather to keep the sun off the clear plastic of the pump. As we all know from either headlights or pump covers, sunlight has a tendency to yellow and haze clear plastics over time.

 

[CaptainCannonball]

I wonder if the duckbill being plugged caused pressure to increase and consequently cause the tube to fail? I've often thought about just removing the check valve, because what really is the point? Your experience kind of nudges me towards removing it, hopefully somebody will chime in.

 

[Bama Rambler]

The only issue with removing the check valve is if the pump tube or the injection tubing springs a leak between the pump and the injection point you could lose a pretty good amount of water before you notice it.

 

[GoGrabTheNet]

...and given that your pump is a 100psi pump, I would not be concerned with the buildup of salts...

I think the only difference between the regular pump and the 100 psi pump is the inclusion of the check-valve. That's it. From what I can see online vs. my pump, there is no mechanical or visible difference with the pump itself.

In fact, the 100 psi pump (i.e. the check valve) seems to be causing nothing but problems, IMO. Lately, since after changing the tube, my Stenner has not able to output enough chlorine to keep up with demand. My previous calcs of run-time have been falling short. For example, a run-time of 20 minutes should output enough chlorine to change my pool +1 ppm. Doesn't seem the case anymore for some reason.

The only issue with removing the check valve is if the pump tube or the injection tubing springs a leak between the pump and the injection point you could lose a pretty good amount of water before you notice it.

While this is true, this is a better side-effect than a green pool...for me anyway! Since I'm messing with the pool equipment and checking chlorine levels several times a week, I'd notice a leak right-away.

Also, it's beginning to look like plumbing the output line of the Stenner into the suction side of the pump is the way to go. Being on the pressure side, despite my Stenner only running when my VS pump is on low is proving to be a defective setup right now. My question with that, however, is if the little rollers don't fully compress the tube in the right spots, then will the suction continuously draw up chlorine?

Actually my opinion of the Stenner pump, in general and the actual product, is going lower and lower almost on a daily basis until I figure out what's going on. I can't see how the use of these devices in any real setting, especially a light industrial one where they most likely are used (i.e. the use of acids, soaps, chemicals, etc.) makes any practical sense...given how sensitive they are.

 

[Bama Rambler]

There is a little more difference between the 100 psi and the 26 psi models, depending on the tube you use, than just the check valve. A couple of the tubes aren't rated for 100 psi, but that's the only differences.

The check valve adds such a little bit of head to the pump that it won't affect the pump output unless something else is wrong with the pump.

How old is the pump?

Do you have the old style or new style pump head?

If you have the new style, when you replaced the tube did you release the rollers so they press against the tube completely?
Did you replace the tube with the same number tube as before (not that it should matter)?

I have used these pumps for years in an industrial environment pumping various liquids, including acids, caustics, flocculants, etc.; and they've always held up well. The pump tube is about the only regular maintenance item there is on the pump. Once in a while I've seen the roller springs get weak and that can cause them not to produce the rated output, but that doesn't happen often.

 

[GoGrabTheNet]

There is a little more difference between the 100 psi and the 26 psi models, depending on the tube you use, than just the check valve. A couple of the tubes aren't rated for 100 psi, but that's the only differences.

The check valve adds such a little bit of head to the pump that it won't affect the pump output unless something else is wrong with the pump.

How old is the pump?

Do you have the old style or new style pump head?

If you have the new style, when you replaced the tube did you release the rollers so they press against the tube completely?
Did you replace the tube with the same number tube as before (not that it should matter)?

I have used these pumps for years in an industrial environment pumping various liquids, including acids, caustics, flocculants, etc.; and they've always held up well. The pump tube is about the only regular maintenance item there is on the pump. Once in a while I've seen the roller springs get weak and that can cause them not to produce the rated output, but that doesn't happen often.

Thanks for the information and reassuring me that these pumps are indeed durable and should work well. I guess my pump is the new style? Not entirely sure. I did, though, snap the rollers into place (against the tube) after replacing the tube. The instructions had me take one of the latches off and insert it into the back of the motor as a keyed lock.

Right now, I am battling a severe problem with my pool chemistry. The water is crystal clear but because of the issues I have faced with the Stenner, I had some algae growth on the walls and on the skimmer tiles. I've been SLAM'ing since yesterday morning. OCLT was about 5ppm at the start, brought FC levels up to 28 ppm, and after a test just now, I lost 8 ppm for a value of 20 ppm in 7 hours! The sun's been beating down on my pool (because Phoenix!), but my CYA is 50-55. Water is very warm (because Phoenix!) between 90-95 daily. Evaporation is pretty high right now, but the auto-leveler maintains it. I don't recall having such a problem last year. The Stenner definitely exacerbated the problem. It sucked my chlorine tank down sooner than expected, and the pump itself failed. That's a double-whammy that has contributed (not caused) my pool to want to EXPLODE with algae any second now!

 

[Topher55]

After two years I noticed my chlorine tank filling back up with water. My first thought was the check valve, opened it up and sure enough all caked up so I switched it out. A few weeks later same thing. I started to wonder how it worked fine for two years then this. Did some research and turns out the spot where the rollers pinch the tube acts like a check valve and my tube was worn enough to let water back through into the tank. Switched the tube out and no problems for over a year, I should probably get a spare on order soon [emoji3].

 

[GoGrabTheNet]

Today, my pool dodged another bullet. It is October 10th, and I have experienced another failure of the Stenner #2 tube. That's a little over 3 months between failures! Luckily, I caught the FC level at around 2-3ppm, so thankfully no algae outbreaks!

This is about the same location where the other, previous tube failed. Also, I noticed that the tube's "rubber" is quiet stiff, and it retained its "squished" shape even outside of the roller housing.

I don't know what's causing these failures, but a tube replacement every 3 months (or 2 months as a good measure) is a wee bit ridiculous. The Stenner pump sits outside, but it is shielded via the rubber-boot cover and the rain hood. It does get exposed to sunlight, but it's honestly not that bad. Furthermore, it does not run during the hottest part of the day, as the pool pump shut off during the hottest part of the day which coincides with the electric peak. The Stenner manual states nothing about limiting usage to cool weather, AFAIK. Perhaps the rubber cannot withstand the super-dry air here in the desert Southwest? Either way, Stenner is going to receive an email. Perhaps they can recommend something.

 

[JoyfulNoise]

Perhaps the liquid chlorine (and dry/hot air) is causing the tube to become brittle as it looks like the liquid pressure is causing the tube to burst.

Perhaps the Stenner folks can recommend a replacement material better suited for liquid chemicals like chlorine.

 

[GoGrabTheNet]

Perhaps the liquid chlorine (and dry/hot air) is causing the tube to become brittle as it looks like the liquid pressure is causing the tube to burst.

Perhaps the Stenner folks can recommend a replacement material better suited for liquid chemicals like chlorine.

I certainly hope so because the "santoprene" material is garbage.

 

[JoyfulNoise]

Santoprene is chemically resistant to chlorine so my guess is this is likely caused by the extreme heat we get in AZ. The unit may not be in direct sun but Phoenix hits 115F regularly in the summers with low humidity which makes for a challenging environment.

Is that break on the pressure side of the tube or the suction side? You said it always fails the same way, right?

 

[GoGrabTheNet]

Santoprene is chemically resistant to chlorine so my guess is this is likely caused by the extreme heat we get in AZ. The unit may not be in direct sun but Phoenix hits 115F regularly in the summers with low humidity which makes for a challenging environment.

Is that break on the pressure side of the tube or the suction side? You said it always fails the same way, right?

True, I did say that, but I guess I meant that the failures/splits are always occurring right near the plastic, threaded ends. Unfortunately, I did not pay attention to what side the failure is on. If I were to guess, it may have been on the suction side. If it was on the pressure side, then I would have seen water flowing out of the crack and the pump housing because a) the split exists before any pinch point of the rollers, and b) the check valve never worked 100%; There was always a little flow of pool water out of it. Furthermore, as I now recall, the end of black, 1/4" tubing (disconnected from the pool plumbing) did bubble/spit during a test operation of the pump. So chlorine solution was being pushed out with pressure but no additional solution was being drawn in due to the split.

The duckbill check valve was still in service prior to this failure. I noticed that the check-valve and the duckbill rubber piece were a bit crusty with salts on a previous day (October 4th per my maintenance log). However, at this time, I did not double-check to see if the tube was split. So now it's the "chicken before the egg" style question: Did the check valve become crusty and cause too much back-pressure leading to the failure of the tube, or did the tube fail which led to the drying-up of the check valve and duckbill?

If I were to put some money on a bet, I would go with the latter since the chlorine solution (and water) would have remained in the tube, keeping it wet. Even if the duckbill because crusty, I would certainly expect a pump rated up to 100psi to clear any salt clogs.

The thing that really gets me is how stiff the tube is, even when new. Why? To me, the tube should be squishy and soft, like a piece of thick latex or silicone tubing. I used to have some thick-walled, silicone tubing used for automotive applications which, IMO, would be perfect for this application. But silicone may not be compatible with a wide array of chemicals.

Long story short (too late): I have removed the duck bill (buh-bye to something so useless), and I have one more #2 tube left. An email has been sent to Stenner seeking advice. If the currently installed tube fails, then we know it will be due to weather. Unfortunately, weather is now getting cooler. It will still be dry, but certainly not as hot.

 

[Bama Rambler]

I've been using Stenner pumps in pool and industrial service for years and I've only seen a couple of failures like that. And those tubes were a lot older than three months. I've never used the pumps in the AZ heat, but it gets 100ºF or hotter here during the summer, but the humidity may be the difference. It regularly runs near 100% RH. Hopefully Stenner can shed some light on the failures and we'll all learn something.

The reason the pump tubes are so stiff is so that they will withstand the pressure and so that they will return to shape after the roller has passed them. The returning to shape is what causes the suction the pump creates. Those tubes were designed to pump very viscous liquids (molasses, mayonnaise, honey, etc.) so the tubes need to be stiff in order to create enough suction to draw those liquids into the pump.

 

[JoyfulNoise]

Isn’t 100psi a bit overkill? I don’t really know much about Stenners as I would not use one here in AZ (too hot to keep liquid chlorine outdoors) but it was my impression that most people install the lower pressure (25psi ?) pump for LC dosing. Perhaps the combo of high pressure, hot sun and dry air is driving these premature failures [emoji848]

 

[GoGrabTheNet]

Isn’t 100psi a bit overkill? I don’t really know much about Stenners as I would not use one here in AZ (too hot to keep liquid chlorine outdoors) but it was my impression that most people install the lower pressure (25psi ?) pump for LC dosing. Perhaps the combo of high pressure, hot sun and dry air is driving these premature failures [emoji848]

You may be right about the heat and the overall harsh environment. With that in mind, I kept my chlorine tank relatively small, only a 5 gallon bucket with a screw-on lid. The bucket is buried up to where the handle goes in. This keeps the temperature down-slightly-because as we central-AZ residents know, even the soil is HOT during the summer! But due to the high usage of chlorine during the summer under the blazing sun, the bucket is emptied in about 10 days. Fresh chlorine solution remains pretty powerful.

Anyways...I believe the 100psi rating only applies to the use of the check valve and the duckbill, AFAIK. Without these items, my Stenner pump is only good for 25PSI, which is more than adequate to exceed the pressure in the plumbing when the VS pump is running at full speed.

 

[Bama Rambler]

All except two of the pump tubes are rated for 100 PSI. The thing that makes the pump system certified at 100 PSI is adding the injection check valve. That's just in case of a leak in the tubing. It keeps the process fluid from spewing out of the leak. The pump will actually pump into a 100 PSI process without either the check valve or the duckbill.

 

[gary300]

Today, my pool dodged another bullet. It is October 10th, and I have experienced another failure of the Stenner #2 tube. That's a little over 3 months between failures! Luckily, I caught the FC level at around 2-3ppm, so thankfully no algae outbreaks!

This is about the same location where the other, previous tube failed. Also, I noticed that the tube's "rubber" is quiet stiff, and it retained its "squished" shape even outside of the roller housing.

I don't know what's causing these failures, but a tube replacement every 3 months (or 2 months as a good measure) is a wee bit ridiculous. The Stenner pump sits outside, but it is shielded via the rubber-boot cover and the rain hood. It does get exposed to sunlight, but it's honestly not that bad. Furthermore, it does not run during the hottest part of the day, as the pool pump shut off during the hottest part of the day which coincides with the electric peak. The Stenner manual states nothing about limiting usage to cool weather, AFAIK. Perhaps the rubber cannot withstand the super-dry air here in the desert Southwest? Either way, Stenner is going to receive an email. Perhaps they can recommend something.

Remove the roller assembly and take a good look at it. The rollers must turn freely or they will mess up the tube in short order. You might just want to replace the roller assembly to make sure.