To prevent future drain fly infestations, clean your drains (they live there not in the tank) once a week. Start by dumping 1/2 cup salt down the drain. Then dump 1/2 cup baking soda down on top of it. Follow that with 1 cup of plain white vinegar, and let the fun begin.
08 Holiday Rambler Vacationer XL 38PLT Workhorse R-26 UFO gas pusher,
2014 Cadillac SRX AWD, SMI Smart Box braking system.