Hi Matt, I use a product called mosquito dunks. They look like donuts and work like a charm, lasting for about 3 months. There is also a liquid called BT - bacillis something or other. It works just as well.

My spouse uses goldfish, about one for every thirty gallon, and has no mosquitoes.

Also Mosquito fish eat the misquito larvae and there fairly cheap. I remember in 5th grade we would have them and mine had 6 babies. I was so excited until she ate them :( But they do eat them and if there arent any larvae at some point they eat a water plant called elodea.