Hi. Firstly, please excuse me if this is the wrong place to post this. Basically I need to find a way I can fill and drain water from one tank to another every 30 mins. The tanks are part of an aquarium and will hold 100 litres if water each. They sit one on top of another. the top one is filled via pump by the bottom one. The top will need to fill to a point then drain then a delay for 10 mins or so until the process is repeated. ive tried with a bell syphon but after a while the gunge in the tank makes the syphon prone to failure. I was thinking of some kind of valve that opens to let the water out fairly quickly. Or trying to think if a way I could use an electron magnet as a value of some type. There must be an obvious solution but I just don't know what it is !!