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Thread: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum side

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    Chlorine injection tube location? Before or after pool pump? Pressure or vacuum side

    I have purchased a Stenner pump and am about to start hooking it up, but not sure where to locate the injection point of the chlorine? Should it be before the pump where the pump is pulling the water? at the pump somewhere? or after the pump? If attached before the pump, there will be a bit of vacuum pulling the chlorine, if after the pump, Im guessing there will be a sort of pressure pushing the chlorine back into the injection tube?

    Any thoughts would be greatly appreciated!

    Reese
    22K gal, IG plaster, hayward 1500 pump, DE filter, spa, Polaris 3900

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    Mod Squad Bama Rambler's Avatar
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    Put it somewhere on the discharge of the filter, preferably after all other equipment.
    Not that it matters in the placement, but did you get the low pressure or high pressure pump?
    Dave J. TFP Moderator
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    Isaac-1's Avatar
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    Also remember that chlorine will outgas, so to avoid potential air lock in the line you want to keep them running upward to the injection point as much as possible.
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    Quote Originally Posted by mystrwizard View Post
    I have purchased a Stenner pump and am about to start hooking it up, but not sure where to locate the injection point of the chlorine? Should it be before the pump where the pump is pulling the water? at the pump somewhere? or after the pump? If attached before the pump, there will be a bit of vacuum pulling the chlorine, if after the pump, Im guessing there will be a sort of pressure pushing the chlorine back into the injection tube?

    Any thoughts would be greatly appreciated!

    Reese
    Do you currently have an in-line chlorine feeded (a puck feeder)? If so, you can move the water inlet to the upper hole (you will have to get the longer feed hose for this though), and screw the chlorine injection valve into the lower hole. This is how I did mine. You don't have to drill anything, and it made for a really clean install. Here's the thread where I learned about doing it this way. http://www.troublefreepool.com/threa...-pump-injector. Notice the first and second pics in the thread.
    Dallas, TX. 27,000 gallon in-ground free-form gunite. Built in 2007. DEL60 filter with single speed 2hp Hayward pump. Polaris 360 cleaner with associated booster pump. Stenner chlorine pump and tank. Intermatic P1353ME timer.

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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    Quote Originally Posted by Bama Rambler View Post
    Put it somewhere on the discharge of the filter, preferably after all other equipment.
    Not that it matters in the placement, but did you get the low pressure or high pressure pump?
    I ended up getting model 45MPHP10, I guess that is high pressure.
    22K gal, IG plaster, hayward 1500 pump, DE filter, spa, Polaris 3900

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    Mod Squad Bama Rambler's Avatar
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    I asked because the HP units come with an injection check valve so even if the tubing or pump tube split the water won't flow out.

    Quote Originally Posted by Isaac-1
    Also remember that chlorine will outgas, so to avoid potential air lock in the line you want to keep them running upward to the injection point as much as possible.
    Since the Stenners are peristaltic pumps you don't have to worry about the outgassing issue.
    Dave J. TFP Moderator
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    Is there a downside to putting it in the suction side of your system with a Stenner? I can think of possiblilities why it would be, but don't some do this into the drain plug on the pump basket? I was going to ask about this in my own thread but it seems pertinent here.

    Also, Stenners don't need head on their suction side do they?

    Since you mention it Dave, how do the Stenners overcome gassing when injecting to pressure sides? I've dealt with LMI lots and lots, but never Stenners.
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    Mod Squad Bama Rambler's Avatar
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    The only real downside to injecting it in the suction side of the pump (and it's not just limited to the Stenners) is that if the tubing/fittings spring a leak, it would introduce air into the system and possibly cause the pump to lose prime.

    Peristaltic pumps in general don't need head on the suction side.

    It's all in the way peristaltic pumps move the fluid. They will actually pump air. Not very efficiently, but they will. Since they use a progressively moving cavity it doesn't stop the flow if some gas gets into the system.
    Dave J. TFP Moderator
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    Well, I wasn't thinking of that, but thanks, that is a good thought for sure. I was afraid there could be enough vacuum to pull bleach through the pump uncontrolled. I guess the vacuum isn't strong enough.

    Thanks for all the info Dave, I appreciate it.
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    As a general rule chlorine injection is always after everything else. Injection pumps with high flow rates (rare) could raise the FC level enough to cause a risk to the heater if the injection point is before the heater. There is also some risk of voiding your heater warranty even if the FC level could never get high enough to make any difference.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Mod Squad Bama Rambler's Avatar
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    Quote Originally Posted by Brushpup View Post
    ... I was afraid there could be enough vacuum to pull bleach through the pump uncontrolled....
    If there were enough vacuum it would "suck" the pump tube flat before it would pull anything through the pump past the rollers.

    And as Jason said, there are other reasons for not injecting on the suction side.

    And as a side note; the LQ (Liquidator) only works by utilizing the suction to draw the chlorine/water mixture out of the vessel. So it's the exception to the rule.
    Dave J. TFP Moderator
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    Re: Chlorine injection tube location? Before or after pool pump? Pressure or vacuum

    Thanks guys. I clearly wasn't thinking it through. I'll have PB cut in a T for me when he plumbs my equipment pad.
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