UV light for sanitation

[Adkaiser1]

Anyone have any experience (good or bad) with UV light systems for their home swimming pools such as the brand name SpectraLight. I am looking at installing a home pool and the ability of running a much lower chlorine level 0.5ppm seems attractive as I have problems with asthma when swimming in the summer and my wife is Rey concerned about chemicals. Sounds too good to be true and no one I know has one of these systems.

[BigDave]

You are right! it is too good to be true. Outdoor pools get lots of UV light (far more than a unit is likely to produce) from the sun. It's just a waste of money on an outdoor pool.

Respiratory and chemical sensitivity issues are more likely caused by under chlorination than adequate (or excessive) chlorination. When chlorine oxidizes organic material (stuff that falls into the pool and stuff that swimmers bring in), many intermediate products are created. Many of these intermediate products are known to cause problems. Some are lightweight and blow away on the breeze (outdoor pool). Some are further oxidized in the presence of adequate chlorine (and UV - outdoor pool). Without sufficient chlorine, the intermediate products stick around causing issues for those who are sensitive.

Products that claim health benefits from reduced chlorine are really just making the problem worse.

Please read all you can at poolsolutions.com and the stickies in the forums here. Pay attention to the relationship between CYA and chlorine. If you learn and follow the pool care method taught here, you'll spend less time and money on your pool, enjoy it more, and breathe easy.

Welcome, glad you found us.

[chem geek]

You should also understand that a pool using Cyanuric Acid (CYA aka stabilizer or conditioner) in it has a MUCH lower active chlorine level where the equivalent Free Chlorine (FC) is roughly 0.1 ppm in a pool with no CYA. Also, the UV system (and also true with most ozone systems) does absolutely nothing to algae stuck on pool surfaces that never get circulated. So you can't really lower your chlorine level to below that which kills algae.

As for chlorinated disinfection by-products, they are roughly proportional to bather load and the active chlorine level so in a residential pool they are negligible. The worst scenario is a high bather-load indoor pool such as some commercial/public pools and those are the ones that cause the most significant problems in terms of air quality. Also, the UV in sunlight will get rid of some of the chloramines (especially dichloramine) far more effectively than a UV system since the entire pool water volume is blasted by UV and the breakdown of chlorine produces hydroxyl radicals that are powerful oxidizers.

There are many, many pool owners on this and other forums who measure the limit of detection for combined chlorine (CC) at <= 0.2 ppm and furthermore quite a few members who have asthma and have no problems with their pools. In fact, the swimming is helpful to them. If you are talking about an indoor pool or one not exposed to sunlight, then that's a different story where supplemental oxidation from UV or ozone may be helpful, but it's a waste of money for an outdoor low bather-load residential pool.

[PoolDoc]

. . . membership upgraded.

Mark and Richard have covered the basics (and a little more) of UV units on pools for you. If you need more, I can find some of the very extensive discussions from the last 2 years, covering the specific topic of UV units AND also the topic if chemical sensitivity. But here are the key points:

1. UV units can have a legitimate application on INDOOR chlorinated pools.

2. We have seen no evidence (and we HAVE looked) that there is ANY legitimate reason to use UV on outdoor pools.

3. We have seen no evidence (and again, we have looked, for years) that either chlorine allergies OR chlorine sensitivity exist.

4. But there is MUCH evidence that sensitive or allergic responses to various chemicals that form in chlorinated pools that are (a) mis-managed or (b) indoors with heavy use. However these chemicals are not present in uncovered outdoor chlorinated pools.

5. Dermatologists currently treat many skin conditions, in both adult and pediatric patients, with "bleach baths" of 50+ ppm free chlorine. These levels are 10x typical pool levels.

6. When mass media journalists write about chlorine topics, they often make SERIOUS errors in describing the chemistry of the situations on which they are reporting. In other words, they spout BS because they don't know enough to tell the difference. But they do know that paranoia and fear sell ads. This is an extension of the old newspaper adage, "if it bleeds, it leads"! As a result, most everything most everybody 'knows' about chlorine is false.