We've already started out obligatory annual UV or ozone thread!

It's in the China Shop, here: http://www.poolforum.com/pf2/showthread.php/24337

That's the long answer . . . and getting longer.

The short answer is, don't waste your money!

If you're concerned about dog => people infections, there are a few things you can do:

1. Make sure you are keeping your FC at the upper end of the appropriate range => http://pool9.net/cl-cya/

2. Use polyquat 2x per week => http://pool9.net/polyquat/ (Helps with filtration and sanitation.)

3. Make sure your pump runs for 4 hours after any dog use.