UV use?

[BND]

What are the opinons on the use/efficiency of UV sanitizers for pool water?

[waste]

BND, while I no nothing about the use of UV for pool sanitation, it is my understanding that viruses are fragile ~DNA threadlets and that UV and temp extreems kill the little nasties (for all I know, bacterium also suffer from UV exposer). However, Waterbear recently posted something to the effect that ' in and of itself, UV chambers won't sanitise the pool water'. Perhaps he or chem geek, or some other knowledgable member, will see this and be able to tell you why. I can say, however, that chlorine is the #1 choice for sanitation, it kills quickly and more efficiently than the other sanitisers and only costs ~ $1.80/ gal. (Another benifit is that it enables you to tell some a** what you think of them while in polite company - ie, tell them to "drink bleach!" - I've used that phrase a number of times to my full satisfaction!)

[chem geek]

This link from the EPA seems to indicate (in section 8.2.5) that UV is a reasonable disinfection technique for bacteria and even protozoa such as Cryptosporidium which chlorine barely touches (also Giardia cysts where UV is better than chlorine). However, UV is worse for inactivating viruses than chlorine. In any event, chlorine is still needed as a residual disinfectant in the main body of the pool water.

Technically, if you are going to have a separate stage disinfectant, ozone might be better, but only if chlorine is used as a residual. Though ozone will reactivate bromide to bromine, it can also form bromates. Ozone will also help break down organics so for indoor pools trying to keep CC low, this might be a decent option (compared to using non-chlorine shock, KMPS, weekly).

Richard