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Thread: Pentair 320 - chlorine tower filling, not dispensing

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    Pentair 320 - chlorine tower filling, not dispensing

    Hey all, thanks in advance for any advice on this issue, it's driving me nuts, eating up my weekend, and making my wife irritable as she can't get in the pool!

    I noticed yesterday that our Pentair 320 was not taking in water, and thus no stabilized chlorine was making its way into our pool. This is probably what caused algae to show up in our pool when we opened it after a week of no use!

    I fixed the "no-water" issue this morning by cleaning the screen at the bottom of the tower, as well as removing the control valve and spraying it down. Once I reattached everything and turned the pump on with the chlorinator lid off, the tower filled with water just above the last puck, and I reattached the lid. However, even with the control valve on 5 (max setting), there seems to be no water flow out of the pump - the water just appears to remain in the tower without dispersing. Moving the valve from 5 to 0 and back doesn't appear to cause any water to move within the tower. Filter PSI is at 17, slightly high but I wouldn't think high enough to cause an issue with chlorinator flow.

    Any thoughts on what might be causing this issue? Are there any tests I can do to identify the problem (or that there even is a problem)? I've read that a failed check valve can cause issues, but not sure how to test for that.


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    Re: Pentair 320 - chlorine tower filling, not dispensing

    Here is an image of the chlorinator and valve if it helps:

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    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Pentair 320 - chlorine tower filling, not dispensing

    Take a sample of pool water right in front of the return. Test it for chlorine.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pentair 320 - chlorine tower filling, not dispensing

    Thanks, I thought of that, but my wife shocked the pool this morning so a sample from the return could be a false positive at this point, and I want to fix this ASAP so we don't get another bloom - it just took us a week to clear up the pool from algae.

    I'm thinking that since the tower is filling with water even with the cap on, air might be escaping from the top preventing a buildup of enough air pressure to push the water out of the tower to the return. Going to check the gasket now.

  5. Back To Top    #5

    Re: Pentair 320 - chlorine tower filling, not dispensing

    Took out the O-Ring and re-situated it in the cap. Re-attached the cap, and now air seems to be staying in the tower instead of escaping, and the water (covering about one and a half pucks) does seem to be agitating a bit. If that was the entire problem, I guess lesson learned, look for the small issues first

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    Join Date
    Jun 2007
    New Jersey

    Re: Pentair 320 - chlorine tower filling, not dispensing

    There is another hole for the valve towards the top of the tower. You need to screw the valve in there and get a longer hose to connect to the other tap if you use 3" pucks and flow is unsatisfactory. The lower hole is for 1" pucks. The manual explains this. I have no idea why they ship it that way. You'd think they would give you a long enough hose to do the top, and let you cut down to use the bottom. Also look inside the big hole the tower screws into. If there is a soft rubber flow reducer, and your pool is over a certain size, it needs to be removed. My idiot PB made both these mistakes. [EDIT: I looked on-line. The newer manual does not talk about the flow reducer, so I guess that changed since 2004. But look anyway, if yours is an older unit.]

    Of course, if you hang around this forum long enough, you'll stop using the silly thing altogether, as I did. It's been in the basement since 2006. Continuous use of pucks will drive your CYA level up and eventually you will get algae whether it works or not.

    Leslie's sells the longer hose:

    Here is the Installation Manual:
    Current: 28,000G 18'x36' I/G AnthonySylvan Plaster; Waterway 60 sq.ft. DE Filter; 1.0hp x 1.65 SF Two-Speed (B2982) WhisperFlo; 2004-Present
    Previous: 40,000G 20'x40' I/G Koven unlined WWII salvage 5/8" marine steel; Lomart Stainless Sand Filter; 3/4hp Hayward SuperPump; 1946-2003 (managed by me from about 1964)
    Ancient Taylor K-2000, upgraded with Taylor CH, TA, and FAS-DPD, and TFT CYA tests.

  7. Back To Top    #7

    Re: Pentair 320 - chlorine tower filling, not dispensing

    Thanks for the very helpful reply Durk. I just "inherited" this pool setup from the previous owners, and I'm sure they likewise inherited it, so no idea who installed it this way. My first summer with the pool, so still learning a lot. I will pick up the longer hose, maybe that will be a small project for next weekend.

    As far as continuing to use the existing chlorinator, a SWG would be ideal but there are other, more important projects to be done/spent on for now. Maybe an SWG will come for Christmas

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