I have a 30 foot cistern overflow drainpipe (6" dia) and mosquitoes fly all the way up it to lay eggs in the water inside the cistern. (The cistern collects rainwater from the roof for the garden) I need a way to allow overflow water to exit but stop mosquitoes. I have thought of slipping an inner tube over the exit to act as a sort of pinch valve. Idea is that the tube will collapse when no water is flowing and stop the little pests. It's hard to find a junk inner tube nowadays so I thought I would ask for alternate suggestions before I buy a new one.
Bob
Bob