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Thread: UV and FC levels

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    UV and FC levels



    I ended up going with Chlorine and UV for my pool instead of SWG. I was advised that the salt water is more corrosive which will decrease the life expectancy of the equipment and could cause rusting if the water comes into contact with the pool panels. From what I have read this is an on-going debate. With the $$$ investment of a pool we felt we went the safe route and didn't go with salt.

    If I use chlorine with a UV system, what should my FC level be at?

    The pool store I was at last year said 3ppm for chlorine only and 0.5-1.0 ppm for chlorine + UV as the UV equipment kills the algae, etc.

    I trust TFP more than the pool store, so what are your thought on a UV system and the FC levels?
    76549 Liters -- Cartridge Filter -- In Ground -- Vinyl -- TF-100 Test Kit -- AquaVac Robotic Cleaner -- UV Sanitation -- Winter Safety Cover -- Installed 2010 -- Southwestern Ontario, Canada

    Latest Test Results June 25:
    FC - 6, CC - 0, CYA - 40, CH - 110, TA - 90, pH - 7.5

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    JasonLion's Avatar
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    Re: UV and FC levels

    UV doesn't help much at all in an outdoor residential pool. It can only kill things in the water that actually passes through the pump, which means it has almost no effect on algae at all, since the majority of the algae is always going to be out in the pool and not passing through the plumbing at any given moment. UV is most effective in indoor pools and public pools which have CC problems, as UV gets rid of CC quite well. UV is also good against the tiny number of chlorine resistant germs, which are normally only an issue in public pools.

    You should follow the regular FC level recommendations if you want to be trouble free.

    The risks of salt are always greatly exaggerated. Yes, there have been a couple of people who have had dramatic damage. We hear about maybe one a year, and all of them so far have had some fairly obvious risk factor, like soft natural stone, or they did something really stupid like putting the SWG on 100% 24/7 for a month in an indoor pool. Meanwhile there are hundreds of thousands of people who don't have any problems at all.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: UV and FC levels

    I may end up converting over to SWG one day. Do you think the UV system was a waste of money? (No, my feeling won't be hurt)
    76549 Liters -- Cartridge Filter -- In Ground -- Vinyl -- TF-100 Test Kit -- AquaVac Robotic Cleaner -- UV Sanitation -- Winter Safety Cover -- Installed 2010 -- Southwestern Ontario, Canada

    Latest Test Results June 25:
    FC - 6, CC - 0, CYA - 40, CH - 110, TA - 90, pH - 7.5

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    JasonLion's Avatar
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    Re: UV and FC levels

    I do, for a residential outdoor pool UV really doesn't add any value. There is nothing wrong with it, as there is with say copper systems, there just isn't a whole lot for it to do, so not much improvement over not having it possible. The most common comment we hear from UV owners is "I recently noticed that the UV system hasn't been working for a while, but I never noticed any difference in the pool."

    Now if you have an indoor pool, or a public pool, then UV is wonderful.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    dmanb2b's Avatar
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    Re: UV and FC levels

    OK, not to hurt your feelings, but chlorine is all you need.

    A SWG only automates the dispensing of chlorine. It generates the chlorine from the salt in the water. Also, when you add chlorine to your pool, all chlorine products add salt to your water. It is not uncommon for a "chlorine only" pool to have 500-1500 ppm of salt in the water to begin with. This is why we always advise checking your salt level before bringing up salt levels to operate a SWG, unless it's a new pool/fresh fill water.

    UV does not reduce the amount of chlorine needed to keep your pool sanitary. It won't hurt and may reduce chlorine demand some, but not enough to recoup the cost of the UV system, in an outdoor pool.

    Edit...Jason responded, but we are on the same page.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    phipsi1237's Avatar
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    Re: UV and FC levels

    http://waterquality.net/en/ozone/why-use-ozone/

    What I'm getting out of this is that the ozone attaches to some stuff that FC normally would, possibly breaking the compounds apart. As a result, not using as much FC. However, I'm sure the website is a little biased.
    14.5K gal Plaster IGP, Intelliflo VS, EasyTouch 8, SWG, IntellipH, Clear and Clean 420 Cartridge Filter, Attached Spa, H400IDL2 NG Heater

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    Re: UV and FC levels

    [EDIT]
    I first wrote this post thinking of ozone. Sorry about that. With regard to UV, it will not reduce chlorine demand. Though it can be a supplement to disinfection for things like Cryptosporidium and though it can help oxidize chloramines, it doesn't oxidize urea so does not handle the largest component of sweat and urine that needs to be handled nor does it oxidize (or break up) most other organic compounds.
    [END-EDIT]
    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
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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