Should I Get a UV unit for My Pool

[PoolDoc]

The starting point is finding out what's in your well water. Well water from limestone strata is ideal for pools; water from shale strata is often a nightmare. It is possible to operate a pool successfully with heavily contaminated water; I've done so on large commercial pools. But it's tricky, and some staining is inevitable.

The first step is to determine whether your well water is a problem or not. Do the metals bucket test => http://pool9.net/bucket-metals

If it is a problem, and if you have the space, you may want to get a 5,000 - 10,000 Intex pool that you can use to pre-treat the water for your IG pool. Trying to treat metal contaminated water once it's IN your pool is a mess. Trying to treat it in a separate pool, dedicated to that purpose, is much, much easier.

I assume your registration address is NOT your new pool's address? (I just looked up your registation, and Googled the address). Otherwise, I'd recommend filling with surface water, which is almost always metal free. You just have to add enough chlorine to make sure the algae and critters die quickly.

[norman00]

I don't think my wife will allow a second pool (I know it's an exaggeration). I'll try the metals bucket test later this week when we hopefully close and take possession of the house/pool. And no, the house you Googled is not the new one, it's the house we're trying to sell. It's time to leave the lake for someone else. I almost never had to worry about the lake water before a swim (except when they sprayed for weed control). Thanks for the input again.

[PoolDoc]

Do the metals test first -- the problem may not be as severe as you fear.

Re the 2nd pool: keep in mind I'm talking about a small pool, 15' round or so, that can be hidden somewhere. You can transfer treated / floc-ced / settled water from the little pool to the big pool via a small sump pump and a 100' water hose! But, hopefully that won't be needed.

[norman00]

Duly noted but I don't think a second pool is in my future. I will struggle with one. Will do the metals test this weekend.
I went to the house today and the water does not seem to be dropping just based on a mark I made 24 hours earlier, so that's not much of a concern. The pH is down to 7.0 so maybe I should add some Borax? That's a question. FC is down to 27, CC is 0 and the CYA is still well over 100. But the water looks really nice and clean. Temp of the water is about 84 degrees. We finally are cleared to close this Friday so I will have daily access this weekend. Looking forward to the first swim since it was 90 today. Thanks.

[PoolDoc]

Yes, add borax when your pH is low.

BUT, with FC=27, you need to retest your pH using a 1:1 dilution of your pool water with distilled water (gallon jug from Walmart; NOT 'bottled', 'artesian', 'spring' water: DISTILLED). Adding distilled water to your pool water will not change the pH noticeably, but will dilute the chlorine. Very high chlorine levels can convert the phenol red into another indicator, with different colors, leading to invalid results.

[norman00]

Finally, we own it. Won't move in for a couple weeks but it's on my shoulders now. Added Borax the other day and the retest of the pH produced a 7.6 and I did the distilled water dilution. Got the first swim in today, check. Water looks good but the chlorine count is still high. I might need to back off the chlorinator even more. Here's the big news of sorts. A guy tested my water straight from the well and he said the hardness was not crazy at 27, but he said there's lots of iron at 3.5. No time to do the bucket test yet since I'm redoing the kitchen. Thanks for all the input.

[norman00]

An update and a thank you. It's now June 2015 and my pool is amazing, in large part due to what I continue to learn here. So, thanks for that. When we opened the pool this year the water was down and I feared a leak. I was thinking it was leaking last year but my lack of knowledge held me back. Paid a company to go in the unheated (62 degrees) water in May and they found the leak at the underwater light fixture. A common problem I discovered. I am now losing about an 1/8-inch of water per day to evaporation and occasional splash. We've had so much rain this spring I actually need to drain some water to stay below the top of the skimmers. Realized a heater was essential and had one installed a few weeks ago. Only used it a few times but it works great and I haven't even used it enough to see a blip on the gas bill. Very happy so far. This is getting long because I think new owners might learn like I did. My auto chlorinator has been empty and I'm running only on the BBB method. Very happy with that too. Numbers just yesterday after getting another 1/2 inch of rain (1/2 inch rise in the pool) were FC 6, CC 0, PH 7.7, and CYA a week ago was tested at 80, which is down from last year when I used trichlor tabs. Numbers are very stable and predictable so far so I guess I'm lucky. Chlorine drop is slow with light use. I cover most of the surface with those solar rings the previous owner left me. I've added an inflatable alligator and turtle and the ducks have not landed in it in the 3 weeks since. Water quality is great. I love my pool. Thanks again for all the helpful insight.

[FormerBromineUser]

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Yay! Great post!!!

Just a thought... Since your CYA is towards the high end of the CYA range, you might want to consider raising your FC minimum to the corresponding higher end of the FC range. http://www.poolsolutions.com/gd/best...e-chart.html#a

[norman00]

Thanks FBU. I agree with you on the staying on the higher end and normally do. But the rains have been heavy for three days (lowering my FC) and my grandkids were coming that day so I figured I'd add a gallon of bleach after we swam. Appreciate the input.

[bowserb46]

If the pool is not covered, you'll get plenty of UV from the sun. It seems the general consensus around here is that the CORRECT UV system MIGHT be helpful for an indoor pool, but is probably a waste of money for an outdoor pool.

FWIW, according to the American Cancer Society, the UV we get from the sun is 95% UVA and 5% UVB. UVA and even moreso UVB can cause skin cancer, but are only moderately effective at killing bacteria and viruses. UVC, the UV that is used for disinfecting, aka "germicidal UV" is a different part of the light spectrum--approximately 254nm. UVC is the UV used in water treatment. UVC does not penetrate the atmosphere, even at the equator, so you don't get the "good UV" from sunlight (although there is some indication that some UVC might be getting through at the south pole.) So UVC is man made down here at the earth's surface.

The combination of UV and ozone are claimed to eliminate chlorine compounds. In my tests, "CC" is always -0-. There is also evidence that chlorine-resistant bacteria and parasites are killed by O3 and UV systems. For some people the evidence is sufficient to use O3 and UV in addition to chlorine. I won't start an argument for or against, as from what I've read here and elsewhere, the Yes/No for O3+UV seems comparable to the Yes or No, For or Against the value of a manual thumb safety on a defensive handgun. Those opposed will not be swayed in their beliefs, nor will those for. Luckily both groups can have it their way, as it is a preference, not a law.

When considered in the context of the entire cost of a swimming pool and spa, the addition of O3 and UV treatment is not much money. Like I said, FWIW.

Hope everyone had a happy Thanksgiving and has a Merry Christmas.
Bill