_At the October Design and Construction Class held by ARCSA in Portland, Oregon I was listening to Billy Kniffen talk about how the water in a tank could be siphoned out of the tank through the first flush device.  I had not heard about that previously.  As water is flowing through a wet conveyance to a calming inlet a siphon effect could occur.  If you have ever siphoned gas out of a gas tank or similar situation you know that once you create the siphon effect the liquid will pull itself from a higher location to a lower location.  Since a first flush device is set up with an emitter to automatically release its contents overtime, it could then be the place where all the water in the tank is siphoned back up the calming inlet through the conveyance mechanism and out the first flush.  To eliminate this problem you drill a hole in the top of the calming inlet which allows air to enter and break any siphon effect from occurring.  At the last installation we finished the design and tested it by filling the conveyance mechanism with municipal hose water through the leaf eater, which filled the first flush, then filled the wet conveyance until it overflowed into the calming inlet inside the tank.  Next we drilled the anti-siphon hole at the top of the calming inlet and an audible suction release was heard.  Thank you Billy Kniffen and ARCSA for sharing your knowledge and training!