Thoughts on 12V Peristaltic Pump

[camueller]

Thanks for the info.. All I am concerned about is the 12V version having enough head pressure to feed the return side of the pipe. I know the 120V will work with no issues but dropping the cash for that is a little hard to do right now.

No problem! I'll be sure to update you once I get it.

As far as the 12v one, I'm thinking you shouldn't worry much. While you may have pressure in your return lines, it's all headed down stream. If you place your injector in the right place (facing downstream), you aren't going to have water trying to sneak back up into your injector. Instead, the water pressure should carry whatever drip your peristaltic pump is putting out.

Honestly though, after looking at the specs, one thing worries me: the <80% humidity rating. Since this thing is going to need some kind of weather proofing box, you'll probably also have to provide some ventilation that moves air well to keep humidity from building up in the box. I'm not sure about where you live, but we get up above 80% humidity pretty often in the summer even without rain. I'm guessing you do too in SC, but maybe not. I'm afraid you could end up going through so much trouble/building weatherproofing that you get close to the $230ish dollars it cost me for the Stenner pump.

Not to dissuade you. I may be wrong about weatherpoofing costs, or the sensitivity of the thing to humidity.

 

[mas985]

While you may have pressure in your return lines, it's all headed down stream. If you place your injector in the right place (facing downstream), you aren't going to have water trying to sneak back up into your injector.

That doesn't matter. What matters is the pressure at the injection point and the max head of the pump. If the max head of the pump is below the injection pressure, nothing will be injected.

The fish tank injection pumps are meant to pump chemicals no more than a few feet high which is only a couple PSI. The injection point will need to be as far from the pump as possible to even have a chance at working.

This pump only lifts 30" which is about 1 PSI:

Aqua Lifter Aqualifter Pump by Toms Aquatics AW 20 Drip Dose | eBay

 

[joshua5438]

That doesn't matter. What matters is the pressure at the injection point and the max head of the pump. If the max head of the pump is below the injection pressure, nothing will be injected.

The fish tank injection pumps are meant to pump chemicals no more than a few feet high which is only a couple PSI. The injection point will need to be as far from the pump as possible to even have a chance at working.

This pump only lifts 30" which is about 1 PSI:

Aqua Lifter Aqualifter Pump by Toms Aquatics AW 20 Drip Dose | eBay

I could not find any specs of the peristaltic 12V pumps. Guess thats something I will have to continue researching. I would rather not use the one linked above.

 

[mas985]

Again, which 12v pump are you referring to? Do you have a link?

 

[joshua5438]

Sorry about that.. I thought I linked it in the last post.

Amazon.com: Homecube 12V DC Peristaltic Liquid Pump Miniature Dosing Pump Hose Pump for Aquarium Lab Analytical Water: Industrial Scientific

 

[mas985]

I have seen those on ebay (for less) under many different manufacture names. I haven't found any data on those either but the head and the motor are very small so I wouldn't expect too much out of those.

However, there is one way around this issue. You could run the chemical pump right before your pump run time and pre-load the return pipe full of however much chem you need for the day which should not be a lot anyway.

 

[joshua5438]

That is a good thought Mark. I am still undecided. I finally have the free Dosatron in hand but I feel it would need some type of valve to help regulate the amount of chlorine added. I am just trying to search all my options before I pull the trigger on purchasing anything.

 

[Randyholcomb101]

Hey,

ya I'm new to this site but all the pools I manage have those pumps. The ones I deal with are Rola-chem but they all operate the same accept some are capable of pushing more gallons per day then others but anyways to answer your ? All of the pools I take care of they are mounted on the wall in the pump room and the supply hangs down into a carboy (liquid chlorine container) and the return goes directly into the main drain. It's just a little hole they made just big enough to fit the surgical tube with a thread and bolt set up. The only trouble I'm having is trying fig out what setting to keep it on....

 

[wmwinn]

I recently bought an aquarium peristaltic pump (https://smile.amazon.com/gp/product/B01HRPKAWI/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1) and ran a few experiments with very good results. With a 9V power supply, this pump can move an ounce of liquid every 30sec. My plan is to inject acid into my super hard water pool (CH=800) as a method to keep calcium scaling at bay. This little pump is so much cheaper than a stenner!

 

[joshua5438]

That is what I was going to try out but I found a used stenner pump on craigslist for $50. Been using it since opening the pool this year and have been very pleased with the results.

 

[SeaCorey]

What power supply and timer are you using with that pump?
The Dosing Pump12V DC Peristaltic Liquid Pump.

 

[wmwinn]

What power supply and timer are you using with that pump?
The Dosing Pump12V DC Peristaltic Liquid Pump.

I am using 120VAC from my solar controller box, which only gets electricity when the main pool pump is ON. I connect that to a standard appliance timer to control when the 12VDC liquid pump comes on. Then, I power the pump with a 9VDC (600mA) wall wort. So far, it's working good.

 

[SeaCorey]

Thanks. Can this pump handle injecting on the return/pressure side? I'd like to plumb it to the return just before it goes back underground and to the pool.

 

[slickraft]

I have been using a cheap Amazon peristaltic pump for about 6 months and inject CL on the suction side about 24" ahead of the pump itself. I plan to move the injection point to the pressure side (after the filter) this weekend as part of a test (and my own curiosity) before I do some other plumbing changes. I think my cheap PS pump will have no issues but I'll let you know. I use a sprinkler timer to run the injection pump because I can easily adjust the run time and have multiple daily start times. I can also do a chlorine boost after storms or high bather loads by selecting "run one zone now" on the key pad and dialing in my desired zone run time. The pump is 12VDC so I also have a cheap 24VAC/12VDC converter placed on the output of the sprinkler that runs it well. The assembly is in my garden shed which is next to the pool equipment pad. The sprinkler timer also runs my automatic Jandy valves so it serves multiple uses.

 

[SeaCorey]

Great timing Dave - for me anyway... I'm going to pull the trigger on a setup and am curious how your test works out.

I had 3 big trees that were right next to the house and shaded the pool almost all day removed in May, and I need an inexpensive system to bridge the gap to the SWG that probably won't happen until next spring.

 

[slickraft]

As mentioned earlier, I use a generic Chinese 12VDC aquarium dosing pump for CL injection on the suction side of the pump. As a test, I moved the injection location to about 2' past the filter. The pump was still able to inject CL even with the filter indicating 16lbs of back pressure so at least mine can overcome some head pressure if needed. Either choice of injection location has failure points but I think suction side is safer and easier on the peristaltic pump and more importantly, the feed lines are not under pressure when you inject on the vacuum side.

This is the pump I'm using because I originally thought the adjustable speed would be handy. Since I ended up powering it through my sprinkler timer I don't use the power pack and set the speed control on high. I adjust the injection time on the sprinkler timer. eBay $24.99
New Dosing pump Peristaltic dosing Head Tube For Aquarium Lab Analytica water MT

I bought this simpler pump as a backup but until the first one dies I have no reason the change it out to see how it compares to the first. Amazon $12.99
https://www.amazon.com/gp/product/B00KJ5X1NY/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

[SeaCorey]

Interesting, thx for the update.
I just ordered JECOD/JEBAO DP-2 Auto Dosing Pump 2 Channel Brand New FREE SHIPPING Warranty | eBay. A little more $ total, but it's plug-n-play and has 2 pumps if I need to pump acid or the first one craps out for some reason.
I plan to try plumbing it to the pressure side, but as it returns down the wall from the solar array on the roof. I'm hoping the pressure will be close to neutral or even negative as it's falling back down.

 

[mas985]

Interesting, thx for the update.
I just ordered JECOD/JEBAO DP-2 Auto Dosing Pump 2 Channel Brand New FREE SHIPPING Warranty | eBay. A little more $ total, but it's plug-n-play and has 2 pumps if I need to pump acid or the first one craps out for some reason.
I plan to try plumbing it to the pressure side, but as it returns down the wall from the solar array on the roof. I'm hoping the pressure will be close to neutral or even negative as it's falling back down.

As the water drops in the pipe, assuming no air, the pressure increases due to the weight of the water. So the pressure is higher than atmospheric. Otherwise the VRV would open. The pressure should be the solar source pressure minus dynamic head loss through the panels so a bit lower than the filter pressure.

 

[SeaCorey]

I hear you, and thought the same, but after I installed the thermal panels I noticed little air bubbles coming from one of the jets.
I harvested the panels and the 2" PVC up-to-back-down-from the roof valve and manifold from a solar electric customer, the VRV was screwed into a Tee fitting w/1/2" threads plumbed just above the shut-off valve, just over halfway up the wall in the piping coming back down the from the array.

The VRV was slightly sucking air.
I could hear and feel it sucking air and turned the valve slowly until the water backed up and the VRV seated and the bubbles stopped.
A 1/2" threaded PVC plug and some teflon tape stopped the air infiltration.
Certainly the pressure at the bottom elbow is higher with the weight of the water and the back-pressure from the return nozzles, but it seems the water "falling" down the pipe was somehow creating a slight vacuum. The system could easily be compromised with a little leak at a joint somewhere but I don't see any water getting out, and it's very easy to access and inspect.

 

[mas985]

I am guessing you are running your pump at low speed? Combined with the lower VRV (only way that could work), the pressure at the VRV can be below atmospheric. If the VRV is sucking air, it means the pressure at the top of the panels has a much higher vacuum (i.e. lower pressure). All the pressure points in a closed plumbing system are relative to the pump pressure and when running on low speed, pump pressure is lower. But that does not negate the fact that rising water loses pressure and falling water gains pressure. That's just physics.