I am having a problem with the check valve on my main line cavitating with the back pressure in the line when the pump power is cut. It is actually kind of fascinating because the check valve in clear and you can watch the never ending rhythmic cavitation of the flap even though there is no power or energy to the system. But the neat part last about 5 seconds when you realize that if the power goes out when you are not there the tank will drain to the bottom eventually. It would probably take 3 to 4 hours to empty with the rate of cavitation but I would rather be safe then sorry. Does anyone have any ideas about preventing this - I do not have much room to work with. I will post a picture tomorrow.
i dont use a check valve at all. to prevent drainback i just drilled a couple of small holes just above the water line in my pvc pipe. when the power fails air sucks in and breaks the siphon. you have to make sure the holes are clear, but thats easy there should be a small stream of water coming from them. and your setup has to be with your return run over the top of your tank.
