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Thread: UV - Lower FC

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    UV - Lower FC

    Moderator Note. This was moved out of this thread.
    Recurring Green Algae after Slamming and Passing OCLT

    Quote Originally Posted by tim5055 View Post
    Yup, with the UV running its like the sun on the pool all the time. If you ran the pump a lot at night you were basically extending the daylight hours on the pool.
    but theoretically you could maintain a lower than otherwise needed FC level. right? this is off topic for this thread but I may search about this. I am flip flopping on whether to run mine or not.
    10,500 gal IG, Topaz Pebble, auto-level
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    DaninFLA's Avatar
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    Re: Recurring Green Algae after Slamming and Passing OCLT

    never understood UV on pool. I know it just a gimmick and something to sell...but um, what about all that FREE UV you get from that bright object in the sky?

    - - - Updated - - -

    Quote Originally Posted by BuckeyeChris View Post
    but theoretically you could maintain a lower than otherwise needed FC level. right? this is off topic for this thread but I may search about this. I am flip flopping on whether to run mine or not.
    waste of money. indoor pool? completely different. they worked great on my fishtank
    Dan
    9,000 gallon in-ground Saltwater pool, plaster, cartridge filer, 1.0 hp pump, Hayward T-15 SWCG, TF-100
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    Mod Squad tim5055's Avatar
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    Re: UV - Lower FC

    but theoretically you could maintain a lower than otherwise needed FC level. right? this is off topic for this thread but I may search about this. I am flip flopping on whether to run mine or not.
    I know chem geek has written about this and that is the sales pitch, lower your FC level.

    Don't turn it on would be my suggestion.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: UV - Lower FC

    It absolutely positively does not let you lower your FC level. Unlike ozone, the UV doesn't kill algae floating through it very much (they are heartier than bacteria). Also, like ozone, UV only kills pathogens that get circulated to it and do nothing for bacteria or algae growing on pool surfaces or that otherwise does not get circulated. So you cannot have a lower FC level in the bulk water if the purpose of that FC is to prevent algae growth and to kill pathogens, especially preventing person-to-person transmission of disease (i.e. for pathogens that don't have time to get circulated between going from person A to person B). This latter argument is more relevant for commercial/public pools -- the risks in low-bather load residential pools is far lower.

    Finally, the UV is a mixed bag since it destroys some disinfection by-products but creates others. It's fine for indoor pools where there is no sunlight so something is needed, but for outdoor residential pools exposed to sunlight there is much more UV from sunlight than from the lamps though the spectrum is different (the UV lamps have more germicidal UV). Also, if you have a very powerful UV system you'll actually use MORE chlorine since the UV will break down the chlorine (same is true for ozone).
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Mod Squad tim5055's Avatar
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    Re: UV - Lower FC

    Thanks Richard!
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: UV - Lower FC

    So the advice is to tighten the gas valve and just forget about it. or unplug it I guess. because the only benefit is it destroys bacteria, but not algae, and my liq chlorine level, which is heigh enough to kill algae, would already kill the bacteria. and while it is killing that bacteria it's also breaking down CL.
    10,500 gal IG, Topaz Pebble, auto-level
    Hayward DE filter, 2HP Ecostar VSP, ProLogic PS-4, GVA actuators
    Cal Pools Wave Force Plus (wall return jets plus 2 floor pop-ups), Venturi Skimmer
    Water sheer, 2 wok pots, bubbler stem on the baja step
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    Re: UV - Lower FC

    ok, I realized I was mixed up. I don't have a UV light, I have an ozonator. there is a tube that runs from the unit into the pump basket and the gas gets sucked down the tube when the pump runs. Bubbles come out the returns.

    I will re-read chem geeks post, as there is some difference between ozone and UV. at least, potentially, the ozone gets circulated a bit in the water. have to search to see if ozone eats up CL the way UV does.
    10,500 gal IG, Topaz Pebble, auto-level
    Hayward DE filter, 2HP Ecostar VSP, ProLogic PS-4, GVA actuators
    Cal Pools Wave Force Plus (wall return jets plus 2 floor pop-ups), Venturi Skimmer
    Water sheer, 2 wok pots, bubbler stem on the baja step
    ColorLogic Mutlicolor LED lamp. Taylor 2006+speed stir

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    Re: UV - Lower FC

    Ozone consumes chlorine more than UV. See "Reactions of Ozone With Chlorine Species" in Chemistries of Ozone for Municipal Pool and Spa Water Treatment. It does not retain a residual in the water because it has a half-life of around 20 minutes while turnover times are many hours (see "Decomposition of Ozone in Water"). Again, an ozonator does not make sense to use in an outdoor residential pool because the bather-load is low. It's useful in a commercial/public pools that has a high bather-load as described in the link. It is also useful in residential spas.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: UV - Lower FC

    so, take the whole AC branch offline at the junction box, open up the pool panel, and disconnect the ozonator power supply to save on energy, is basically the best course of action....
    10,500 gal IG, Topaz Pebble, auto-level
    Hayward DE filter, 2HP Ecostar VSP, ProLogic PS-4, GVA actuators
    Cal Pools Wave Force Plus (wall return jets plus 2 floor pop-ups), Venturi Skimmer
    Water sheer, 2 wok pots, bubbler stem on the baja step
    ColorLogic Mutlicolor LED lamp. Taylor 2006+speed stir

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    Re: UV - Lower FC

    ok, I read (well, I mean, looked at) that article chem geek posted. So you're saying that, if I have clean water, and run the pump overnight, I will experience abnormal OCL just because the ozone is running, irrespective of the CL actually killing other contaminants?
    10,500 gal IG, Topaz Pebble, auto-level
    Hayward DE filter, 2HP Ecostar VSP, ProLogic PS-4, GVA actuators
    Cal Pools Wave Force Plus (wall return jets plus 2 floor pop-ups), Venturi Skimmer
    Water sheer, 2 wok pots, bubbler stem on the baja step
    ColorLogic Mutlicolor LED lamp. Taylor 2006+speed stir

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    Re: UV - Lower FC

    Yes, ozone reacts with hypochlorite to produce oxygen gas and chloride. That is, ozone consumes chlorine. So it only makes sense to use ozone when there is something other than chlorine for it to react with, specifically chemicals where ozone will react more quickly than with chlorine. That means it only makes sense to use in at least moderate if not high bather-load situations. It doesn't make sense to use in low bather-load pools as is the case with most residential pools. This is most especially true for outdoor residential pools exposed to sunlight since the UV in sunlight breaks down chlorine into (among other things) hydroxyl radicals which are very powerful yet short-lived oxidizers. They tend to take care of bather waste that would otherwise be slow to oxidize by chlorine and the UV in sunlight also reduces some chloramines (mostly dichloramine).

    In another forum, there is a very long thread about one person's ozonator experience in their pool where they initially swore that the ozonator was doing some good, letting them use a lower chlorine level, and preventing algae growth. It took a while including having the person do an experiment, but I convinced them that it was not the ozonator but rather their use of a phosphate remover that had their pool be able to use a lower FC/CYA ratio and still not have algae growth. I actually had them add fertilizer to the pool to raise the phosphate level and they could see that even with the ozonator they were not able to prevent algae growth (at the lower FC/CYA level they desired due to the wife not wanting any hint of having chlorine in the pool). They then used a phosphate remover and got back to what they had before.

    The fact that the ozone manufacturers are not forthcoming about how ozone depletes chlorine in spite of the clear known science should give you an idea of the level of integrity of some of those selling such systems.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: UV - Lower FC

    I know TFP deals mostly with pools but a significant number of TFP members (yours truly included) have attached spas. Would it make any sense to invest in an ozonator that was only used during spa use? Spa's typically have much smaller water volumes so even if there's only two or three people in the spa (sweating, drinking, etc), then the actual bather load is quite high. I've often wondered if my attached spa would benefit from an UV/Ozone system as opposed to having to dose it with a big shot of chlorine after use to burn up the CCs before allowing it to dump back into the pool.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: UV - Lower FC

    Yes, the ideal situation would be able to have an ozonator you could turn on when you wanted it to run and specifically that would be primarily right after you soak in the hot tub. You generally do not run an ozonator while using the tub unless it has a degassing unit (which most residential units do not have) and many spas automatically disengage the ozonator when you run the jets in order to avoid having ozone outgas since it is hazardous to breathe (it's an EPA regulated air pollutant). You also shouldn't use the ozonator for background dosing because the outgassed ozone is much harsher on spa covers (chlorine outgasses less, especially when CYA is in the water).

    So the ideal would be to soak with a low chlorine level, then get out and turn on the ozonator for around 30 minutes or maybe an hour (ideally with the cover off), then add chlorine mostly for background dosing but also to handle some bather waste that ozone might not handle as quickly.

    The other situation where ozone is useful is with a bromine spa since it will regenerate bromine from a bromide bank though it does also slowly deplete bromine to bromate over time so the bromide bank needs to be refilled. So the ozonator is also useful for automatic background dosing in a bromine spa.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: UV - Lower FC

    Any spa owners want a good deal and a fairly new Ozone unit?????
    10,500 gal IG, Topaz Pebble, auto-level
    Hayward DE filter, 2HP Ecostar VSP, ProLogic PS-4, GVA actuators
    Cal Pools Wave Force Plus (wall return jets plus 2 floor pop-ups), Venturi Skimmer
    Water sheer, 2 wok pots, bubbler stem on the baja step
    ColorLogic Mutlicolor LED lamp. Taylor 2006+speed stir

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    JoyfulNoise's Avatar
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    Re: UV - Lower FC

    Quote Originally Posted by BuckeyeChris View Post
    Any spa owners want a good deal and a fairly new Ozone unit?????
    I'll bid $0 and expect free shipping


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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