SpudFiles

looking for a 12 volt AC sprinkler valve. This valve it to be used with a timer to add water to a pool

I don't think they make them. The industry standard is 24 volts so most of them will work with off the shelf sprinkler controls and timers. It is possible to use a 24VAC transformer with a center tap as an auto-transformer to convert 12VAC into 24VAC. Another solution since you have AC power, is to use 12 volts to power a relay that then powers a 24 Volt valve.

Due to variable conditions, such as sun, humidity, wind, water supply pressure, a simple timer might not work the best at keeping a pool topped off. If the timer is just for filling a pool once such as a 2 hr run time, a sprinkler timer from an irrigation supplier should do the trick out of the box.

Isn't a float switch a better idea?

http://en.wikipedia.org/wiki/Float_switch

You can have a minimum level one to open the valve and a maximum level one to shut it off.

Also: http://www.ebay.com/itm/1-2-Brass-Solen ... 19dab76cc7

Not massive flow but if you're just topping up, it shouldn't really matter.