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Thread: UV System

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    UV System

    I've read all the comments on the UV systems. I was looking at spectralight. I understand the need to still have the chlorination, etc. My interest in getting it is the brochure claims you rarely have to adjust the PH. I was wondering if that's true. I have a 20,000 gallon saltwater inground pool. I'm getting ready to close the pool for winter, but was thinking about it for this for spring when I reopen it. Right now I have to add 1/2 gallon of muriatic acid 2 - 3 times per week to keep the PH at a reasonable level. If the UV system would reduce that down to once a month or even less, then for my purposes, I think it would be worth it. However, if there is some reason it wouldn't be a good idea, I would appreciate all the input.

    Thanks,

    Liz

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    Mod Squad JohnT's Avatar
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    Re: UV System

    I can't see any mechanism where UV would affect the pH. A SWCG, new plaster, high TA or a water feature can all cause rising pH.
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    Re: UV System

    Thanks for the info. I don't want to waste money on it if it won't do any good.

    Liz

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    Christian's Avatar
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    Re: UV System

    Hmm, I just looked over their site and I didn't see anything about their UV system controlling pH. Strange that they would have that in their brochure but not on the site. Smells fishy to me. I am not aware of UV having any effect on pH. The main advantage of UV is that it removes chloramines.

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    Re: UV System

    Christian -

    Thanks for your response. I thought it strange too that you didn't find it on their website. After a lot of searching, I did find it in FAQs on spectrlight's website http://www.spectralightuv.com/faq.html - scroll down to "do I need to still test PH and Alkalinity". I copied the below from their website.

    Do I still need to test the pH and alkalinity?
    Yes, but it becomes much easier. Maintaining proper pH is very important to maintaining neutral water that does not burn your eyes. High chlorine levels and high combined chlorine can cause a high variation in pH. A pool which has UV in use will tend to have a very stable pH and alkalinity, so adjustments will be less frequent.

    My goal is to get around having to add the muriatic acid 2-3 times per week. I didn't put in my original post that the pool is new this year, so maybe as the years go by the need to add it as much as I did this year goes down? I've looked into the automatic acid feeders, but they seem to come with their own set of problems and issues so I ruled it out.

    Thanks for your input.

    Liz

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    Christian's Avatar
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    Re: UV System

    Yeah that line is misleading. It doesn't actually help your pH they are just saying that lower chlorine levels can affect your pH in a roundabout way. Also good to know it's a new pool. The acid requirements will go down significantly once it is done curing.

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    Re: UV System

    If you have an outdoor pool, then a UV system is unlikely to offer any significant benefits. It should not have any effect on stabilizing pH.

    High TA is the most likely cause of your pH rise. Most pH rise from new plaster can be eliminated by maintaining the correct chemistry.

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    Re: UV System

    Thanks for the info. I won't waste my money on it.

    Liz

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    Swampwoman's Avatar
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    Re: UV System

    In addition to keeping you TA around 70 and the drift improving with time, you ay also wish to consider adding borates to 50 ppm as that is truly supposed to help control ph drift. Once I got my TA down to 70 and added borates, I really only ha to add MA about once every 9-10 days.
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    Re: UV System

    Thanks for the info on the Borates and TA. I will definitely try that. It will be much better than having to add MA every 2-4 days.

    Liz

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    Re: UV System

    When I first installed our Intellichlor back in June, I did notice needing to do frequent muriatic acid additions to keep the pH in range. However, our TA at that time was around 150. Using info here, I've managed to get that down to 90 and am moving towards 70 within the next few weeks. At that point, I will follow the suggestion of adding borates to act as a pH buffer. I simply used the method where I aerated the water with our waterfall pump for several hours a week, and added MA to get the pH to around 7.2 about once or twice a week. This has probably taken longer than needed due to my being rather busy at the moment, but our TA is moving in the right direction. So, while the point about UV not increasing the pH may be correct, it certainly doesn't act to buffer pH fluctuations you may see, esp. if you plan to use chlorine as a sanitizer. In addition, UV only kills the stuff that is in the UV chamber, not things growing on the sides of your pool. It would seem to me that mustard algae would simply love to find a UV sanitized pool since they would not necessarily make their way towards the UV chamber. Given this, I don't see any benefit.
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    Re: UV System

    Great. Thanks for the additional information.

    Liz

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