Shrug, the idea is to build failsafes into the exsisting sytem. Like using and aqualifter, excessive overflow capacity.. using multiple pipes incase on fails.. they don't have to all run at capacity they just have to work. If you have a single overflow, make a second one and tie it in wih the system. This way incase for some odd reason the first one fails due to something liek air or another blockage the second one will work. You can use an aqualifter on both to prevent the air issue, so you would only have to worry about random blockage causing failure. These are all very cheap and easy options to build in failsafes. The aqualifter will help in other ways as well such as re-priming after a power outage incase you have an airleak in your system or your overflow is not designed to maintain prime. Just my opinions