Considering UV for a new outdoor pool.

[BigDave]

Sanitizing potable water is different from sanitizing pool water. UV systems can only kill pathogens that are passing through the UV system at the time, they don't kill anything in the pool. Chlorine, on the other hand, is in the pool ready to kill pathogens when they are introduced. No one is completely clean, pool sanitizer must kill the bacteria that washes away from the far end of a swimmer's GI tract before it gets to the near end. UV systems can never do this.

UV systems have a place but not in outdoor pools. That said you can find someone willing to sell these systems with claims along the lines of "reduce the use of Chlorine" and "lets you run lower, safer, chlorine levels". The first reason is just plain bunk, UV destroys chlorine so it's just not possible that it could reduce the consumption. The second reason is worse than bunk, it implies (or supports the notion) that chlorine is "bad", it is not. It also encourages a dangerous reduction in sanitizer level that may leave swimmers very sick.

Please reconsider the notion of using a UV system for an outdoor pool. At best, it lightens your wallet; the downside can be much worse.