Stenner pump system project: Thoughts?

Tomcat77

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LifeTime Supporter
In The Industry
Aug 31, 2013
14
San Diego, CA
Hi again,

Thanks to the people and info here at TFP, I’ve had good success since I converted the five pools I care for to the BBB method. Keeping my water balanced is quite simple, and the benefits far outweigh the ease of throwing tablets in a floater. I’ve learned a great deal reading on the TFP website, and am in search of advice and/or critical opinions.

I’m currently working on a project for one of my clients - with the pool listed in my signature. The pool is large enough that a lot of the year my client adds chlorine midweek. She’s happy to do it, but she’s getting older and I want to relieve her of that chore, so we made a deal for installation of a chlorine injection system. I’ve read just about everything here on the topic, seen some excellent pictures on TFP of setups, and have come to decisions that I’d like to share. I’d appreciate it if any of you would feel free to make any suggestions if you see anything wrong - or any way you think I might make a better system. I’m at the stage where I’m ready to order the pump/tank/timer, and I’d like to run this by the forum first.

I’ve chosen to go with a 120V Stenner 45MPHP10 fixed output pump ($208 from Locke). I picked the 100 psi version because the 25 psi pump is closer than I want it to my max pressure, and the 100 comes with the check valve. I also picked the 10 gal./day pump to run shorter times. The main pump runs about 8 hours a day. I’ve spoken with Pentair, and apparently there is no reasonably affordable way for me to have the Stenner slaved to the Intelliflo as far as having the injection pump running only when the main pump is on. Since I have to have a timer anyway (Intermatic ET1125CR - $97 at Amazon), I took the advice of several members to go with the fixed pump and eliminate the potential problems (and the ‘click’) with the adjustable version.

The current pool equipment is exposed and uncovered, so for appearance’ sake, I’m going with the Stenner 15 gallon tank ($139/no shipping at PoolWeb; better price at Locke but a huge shipping charge), on which the pump will be mounted. I plan to drill and tap the 2” return elbow fitting for extra wall strength at the injection site. I elected not to put a shutoff valve there, as I don’t think the plumbing sets up well for another fitting, but I’ll have a 1/4” plug stored with the equipment should the Stenner pump fail.

I do have a few 'unknowns' at the moment:

1. I realize it’s important to keep the chlorine as cool as reasonably possible. So, it seems I should go with the translucent white Stenner tank, but I prefer the look of the UV gray model. Does this make sense, or does it not make that much of a difference?

2. Is there a "best" time to inject the chlorine, or perhaps I should split it up? I expect to be injecting between 40 and 50 oz. of 12.5% chlorine per day in the summer. Currently, the Pentair pump runs from 0200 to 1000. I saw one setup where the owner put all of the chlorine in fairly quickly at the start of the pump cycle. I’ve seen others where part of it is injected just after sundown and part maybe an hour before the pump cycle ends. I’ve seen some where it’s injected slowly the length of the pump run time (adjustable pump or several start/stops on a fixed pump). Perhaps there’s no “best” time? I’m flexible about the main pump run times, but SDG&E is happier if it runs night/early morning.

3. Slightly off topic: Has anyone come up with a drop test for borates yet? I find the strips pretty vague.

Many thanks in advance for your help/advice. I promise to post pictures of the finished product. :)
 
Great timing on your post. I'm working on a similar system for my own small pool, using parts on hand. I'll be sure to stay tuned to this thread.

Have you considered using a microcontroller to interface with your (her) Intelliflo system? Shouldn't be too hard to implement, with a relay to operate the Stenner.
 
I picked up on a couple of things.
1) Since the equipment is exposed I'd recommend the opaque tank for the chlorine. The heat gain from the tank is going to be negligible over the translucent one.

2) It doesn't matter what time of day you inject the chlorine. For safety's sake, I'd suggest letting the main pump run a few minutes before starting the injection just in case the times get a little out of sync, but other than that it doesn't matter. If you think about the people that pour bleach in once a day, they do it all at one time and over the period of a few seconds.

The setup you have planned sounds like a good setup.

If you think it's important to ensure that the main pump is running before the injection pump can run, you can use a current sensing relay (i.e. Macromatic, etc.) on the main pump power feed to break the feed to the injection pump after the injection pump timer.
 
Hey Charlie,

I'm not familiar with how that would work. The Pentair CSR didn't mention any alternatives - although I didn't ask him specifically - but basically said there was no way to control the Stenner with the Pentair pump. Since the onboard computer controls the Pentair, I don't think I want to put anything in front of the pump. How does that work?
 
Hi Dave,

I've read about your system, from which I've swiped several ideas. ;) Thanks for your input. I'm going to have to read up on the sensing relays. Much of what I've read made it seem really important to have the main pump running before the injection pump, and I can see that. I don't see much of a down side to the Intermatic timer - both the pumps have backup batteries in case of a power outage. Maybe it's not THAT big of a deal if the injection pump goes on without the main pump running?
 
Since both timers have battery backup, I wouldn't consider it an absolute to go to great lengths to ensure that the main pump is running before the injection. It's not very likely that they'll ever get totally out of sync.
 
Dave's current sensing relay would be a better deal for you. Essentially the microcontroller would be doing the same thing, sensing the motor current for your pump, then adding however long a delay you wanted before turning on the stenner for the time you specify.
 
I have the gray tank. Looks nice but I cannot see the level from outside. The translucent may allow you to see the level. Make sure that it is UV resistant like the gray tank. I built a lightweight enclosure out of plywood to protect the tank from direct sunlight. I just didnt want the bleach getting too hot. The tank is UV treated.

I am presently using 8.25% bleach and run the Stenner for 2 - 1 hour cycles 12 hours apart. I run it concurrently with my cleaner cycle which runs the little robot guy.

That's my 15 cents.
 
Charlie -

Dave's thought about putting a current sensing relay seems like a good idea. I had to think about it for a bit, but now see that his idea of putting the break *after* the injection pump timer is the way to go. I'll give this some thought about how necessary it really is, since both timers have battery backups. I'm reluctant to put another variable in, since this pump puts out .89 ounces/minute. I want to be able to depend on the amount that's going in, and the only way for me to do that is with the Intermatic timer.
 

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Puertex -

It would be nice to quickly see the fluid level, but I should have a good idea what's in there, and I always have at least 4 gallons of 12.5% with me. I haven't called Stenner, but everything I've seen from them describes them as "translucent white" and "UV resistant gray". I like the gray color, and its UV protection, but it looks like I may have to cover it to keep the chlorine cooler (It probably wouldn't be a bad idea to cover either of them, though). It seems this might defeat the purpose of using the Stenner tank for appearance in the first place. Can't win for losing..... ;)

Your post is worth a lot more than 15 cents to me - thanks for your thoughts on the tank.
 
Faux,

Sorry for the delay getting back to you. My idea about the tank has changed somewhat. If I need to cover the tank in any case to keep UV/heat down, I'll probably go with the blue 15 gallon HDPE drum for $30 and perhaps make a white Sunbrella cover for it. I've seen your buried drum, which I thought was an innovative and excellent idea, but I can't do that in my case. I do like the look of the Stenner tank along with the ability to mount the pump on it, but if I need to cover it, I might as well go with the much cheaper version.
 
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