actually can lah...but i dun know where exactly the final water level will be due to variations like the return pump and other factors...at least if i use this method..i can vary the length of pipe and joints to ensure not much water flow back in power outage.....i dun want to use a one way valve as it will take out alot of flow from the powerhead....
so if i use the method like u said, when power fails, quite alot of water will flow back into the sump which i do not want...at least with this overhead return method, abit unsightly, but at least i can vary the height of the return outlet to determine when the siphon break will occur....hehe