Drilling return?

[sphelps]

It's a good idea if it's needed. If you can turn your equipment off and your sump can handle the extra water from the siphon then don't drill any break holes. If it can't, drill them just below water surface and at the side of the pipe if possible to avoid spraying water upwards. Be careful though as relying on such things isn't always a good thing as algae will clog them often which can lead to failure. Always best to design the system so such things aren't needed.