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Thread: Ozonator Venturi: restricted flow rate = lack of ozone suction

  1. Back To Top    #1
    Daf-Tekno's Avatar
    Join Date
    Sep 2014
    Calgary / AB

    Ozonator Venturi: restricted flow rate = lack of ozone suction

    Hello Rulers of Pools,

    I recently installed an ozonator along with a venturi to my Jacuzzi.
    It is connected to the 3/4 inch water line that comes off after the circ pump & heater, which is in parallel with the larger line feeding the floor return and waterfall.

    This is where the original ozonator was located (which was removed without my knowledge by Jacuzzi when they fitted a ClearRay UV a year or 2 ago).

    I'm having flow rate issues.
    It appears that the venturi is causing a restriction in the water flow, meaning it isn't generating enough suction to pull the ozone out of the ozonator effectively.

    I tried connecting an ozone 'test tube' between the ozonator and venturi, and it only managed to discolour the tube the first few centimetres, not the entire length.

    I've taken approx. flow rate readings using a bucket, and recorded:
    c.6 L/10s (= c.36 L/min, = c.9.5 USg/min) unrestricted
    c.2 L/10s (= c.12 L/min, = c.3 USg/min) after passing through the venturi.

    It seems a bit daft that the venturi appears to be restricting the flow so much, it can't do its job of sucking out the ozone properly!

    My make-shift solution is to connect an aquarium air pump between the ozonator and venturi to help partially pressurise the ozone into the venturi.
    Another make-shift solution is to connect a water pump into the 3/4 inch line to help increase the flow rate there, thus increasing the venturi's suction.

    Can anyone tell me if this is a usual problem when connecting ozonators?
    Could it be that some venturis are better than others in this respect?
    How does one normally install an ozonator to a spa?

    I strongly suspect that spa dealers go and fit an ozonator and venturi to a spa and don't bother testing its performance.
    So, no-one is any the wiser to the fact that the ozonator is hardly doing anything atall!

    I realise that using the TFP / BBB method, devices like the ozonator and UV lamp are unnecessary for efficient hygiene.
    However, I've already bought them, so I may as well use this situation as an experiment to see if I can get them set up and running as effectively as possible.
    (As long as this doesn't require significant additional expenditure).

    That way, I may be able to offer advise to people on their deployment, successful operation and usefulness in the future through real-world experience.

    Thanks - D
    Last edited by Daf-Tekno; 10-25-2014 at 03:04 AM. Reason: Error grammatique
    Jacuzzi J480 (2008) 1700 litres, Balboa ozonator, Delta EZ-18-120 UV lamp via custom 6-way 2-tier timer solenoid array, 2 x Waterway 4HP main pumps,
    1 x Aqua-Flow 1/15 HP circ pump, ChlorMaker IL SWG, SmartSeal + Roxul skirting insulation, 8' x 8' ThermoFloat Spa blanket, 100" x 100" Gator coverall

  2. Back To Top    #2
    Isaac-1's Avatar
    Join Date
    May 2010
    SW Louisiana

    Re: Ozonator Venturi: restricted flow rate = lack of ozone suction

    I am not sure about Spa UV ozonators, but CD ozonators can generate a nitric? acid byproduct that over time can form gunk that clogs fittings in the venturi and in the tubing, these can be cleared by flushing with about 6 ounces of white vinegar every 6-12 months, just don't let any of the clear acid that may build up in the tubing get on your skin. Simply disconnect the tubing at the ozonator end and put it in a cup of vinegar and let the venturi suck it up.

    However in your case it sounds like you are having flow problems with the circulation pump, as these pumps get older than can fail by getting weaker and weaker, until you start getting low flow problems. I had to replace one on my Hot Spring tub shortly after buying it as a used tub.


    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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