Any problem with running peristaltic pump for short bursts?

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G

Galun

0
Apr 14, 2011
45
Thanks to the help and suggestions I got here, I have finally narrowed down to peristaltic pump as the best option for my chlorine automation. SWG was a contender until wife tried a friend's salt water pool and didn't like the feel. Well, that was it.

I plan on going with Stenner pump + tank combo. Due to the high electricity rates in my area, I plan on running the pool pump in high speed for only 2 hours, and I plan on doing the bleach injection during that time. I am wondering if there will be a problem with getting a "large" pump like 85MHP17 and run it for like half an hour? Based on my spreadsheet calculations, running that at half an hour with 6% bleach at setting of 9 will get me 1 FC. I think there is a lot of flexibility to increase the bleach injection due to temperature and bather load and still keep the stenner run time within the 2 hour main pump run time (I can go up to +4 FC if I run the Stenner for 2 hours).

My concern is the "rapid" injection of bleach. Intuitively it doesn't seem like a concern - I'd be injecting 1/3 gallon of 6% bleach over half hour into pvc pipes that should not be hurt by belach anyways. But I figure I'd make sure with the experts here first.

Thanks!
 
Re: Any problem with running peristaltic pump for short burs

Just curious... If you have a VS pump, why not run it longer at a lower speed if electricity costs are a concern? Correct me if I am wrong, but I thought that VS pumps are much more efficient at low speeds. Also, if you are worried about "rapid" chlorine injection in your proposed 2 hour window, then you would presumably be safer injecting the same amount over a longer period of time.
Are you saying that you will only run your pump for two hours a day? Or just two hours a day at high speed? That is my confusion. I always thought that the basic premise is to turn the water over once a day in the pool, for proper filtration and circulation.
As for the pump and tank, do you plan to use a Stenner Tank (gray w/ attached pump http://www.stenner.com/prod-tanksys.htm) or get some other sort of plastic tank for the chlorine? Inquiring minds want to know. :shock:
Thanks, and keep us updated with your progress, please.
 
Re: Any problem with running peristaltic pump for short burs

>>.. was a contender until wife tried a friend's salt water pool and didn't like the feel.

in case the decision is not ultimate final, please ensure that the pool being "tried" had absolutely optimal chemistry levels. otherwise, how can you/she be certain about the "feel" ?

if the salt was high or chlorine was high, it was not a fair test (..and many other combinations..)
 
Re: Any problem with running peristaltic pump for short burs

It costs less to run the pump at a relatively low speed for longer. With an IntelliFlo the lowest electrical costs for moving a given amount of water are around 1000 RPM.

As long as you know the pump is running and the injection point is a couple of feet after the heater, and all other equipment, you can inject bleach fairly quickly if you need to.
 
Re: Any problem with running peristaltic pump for short burs

Injecting the chlorine in a short time frame is not a concern. Your injection point should be after all your equipment anyway.

You're only injecting about 1½oz per minute with the dial on 10.

After doing the calc I think you're going to have to run the 17gpd pump longer than 30 minutes but that's not an issue either. And as Jason said, you can run the injection pump whenever the main pump is running, not just when it's on high.
 
Re: Any problem with running peristaltic pump for short burs

Thanks!

Voodoo - I am running the VS pump for 2 hours in high speed and 9 hours in low speed to get 1 turn. The reason to run Stenner pump for 2 hours is to save electricity - at 0.9A x 220V it uses only about 200 watts, but at my rate of $0.4/kWh it adds up quickly. Plus I plan on wiring the Stenner pump to a relay on my suntouch and I think I can tie it to my high speed circuit to get synchronized scheduling with high speed mode. I plan on getting the Stenner tank - it's more expensive but from what I read they last forever so I figure the cost can be amortized over a long time.

susa - It's not final yet, but I need to get chlorine automation in soon due to some long upcoming trips. I figure I can reuse the Stenner pump / tank for ph automation down the road if wife likes the feel of salt water pool. Like some here, I think I also have a weakness for tinkering, so I wasn't fighting my wife very hard on the swg :D

Jason / Dave - thanks for the advice. Using the pool calculator, for 20k pool and my current chemical specs, I need 41oz of 6% bleach to raise FC by 1. According to Stenner website, 85MHP17 at 9 gives 15.3gpd => 0.64 gph => 81.6 oz/h. To get 41oz I need to run pump by about half hour. Did I go wrong with my math somewhere? Thanks!
 
Re: Any problem with running peristaltic pump for short burs

Your math looks good, always good to get a reality check. If you needed to draw it out, is there any problem with diluting bleach yourself (aside from reservoir size limitations)?
 
Re: Any problem with running peristaltic pump for short burs

Bama Rambler said:
Your math is correct. It's just that 1ppm per day loss is very low and unusual for most people.
Click to expand...

Cool, thanks. Yup I am only losing 1 right now, but it's still cold out (pool temp in the 60s) and not a lot of sun yet. I imagine that will change quickly as we go into the summer. But with the 2 hour high speed pump circuit I can get to +4 FC so I think I should be ok.

Here's another thing my wife asked - she wants me to "create" the SWG pool water from our pool. She is primarily concerned about taste. Please help me gut check my math.

According to pool calc, For 10000 gallon I need to add 84lbs to salt to raise salt by 1000 ppm. For 1 gallon I would need 84/10000*16 = 0.134 oz. That's slightly less than one teaspoon. I plan on creating the "water" at 1000, 2000, 3000, and 3400 ppm. (I am also thinking about adding some salt to non swg pool just for the feel that a lot of people seem to like).

I think my math is right, but I think there must be a more accurate way by titrating my pool water with a high concentration salt solution, perhaps multiple titrations. Any suggestions?
 
Re: Any problem with running peristaltic pump for short burs

For what it is worth...my wife LOVES the "feel" of our pool, as does everyone else who has ever looked at or swam in our pool. Now, to be honest, I do not know if it is the Borates or the salt, but the water is SO nice to swim in. The DE filter also helps to make the water "crystal" clear, even at night with the light on. While I am not a fan of the SWG, I do believe in salt. They say that some folks can detect a salt taste at 1000 ppm and others don't taste the salt until above 3000 ppm, everyone is different. At 2000 ppm, I can detect the salt, but then again I try not to drink the water. :mrgreen:
Just my opinion, but I added salt to my non-SWG pool and have never looked back. All is well...Voodoo is thy name, and I have a reputation with the local pool stores. :twisted:
 

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Re: Any problem with running peristaltic pump for short burs

I just got this installed yesterday.

Ordered a 15gal drum but stenner sent me a 30gal. Oh well. Works just as well.

I opened up the motor housing to switch out the electrical cord to connect to a relay in my Suntouch panel. The wires are just connected together by wire nuts so it's pretty easy.

The rest of the install was really easy. The unit pretty much came preassembled. Just connect the tube and go. In hindsight I probably could have just ordered the pump and a cheap drum, as stenner pretty much just screwed the pump housing onto the drum anyways. The package does come with a spare pump tube.

It's only the first day but it seems to be working fine. I am getting my expected FC increase by my spreadsheet of runtime and pump speed.
 
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