I would personally avoid a system using an aqua-lifter or similar pump. It opens up way more potential for failure. If you size things properly and use the correct flow rate then bubbles should not build up in the tube and you should never loose siphon.
Your system should be designed to make floods next to impossible. Your sump should be designed so that the return pump runs dry before the display can overflow in the event of a siphon failure. This usually requires an ATO however if an ATO is not an option then a simple float and relay system can be used to shut off the return pump if the water level in the display gets too high. To prevent siphon failure in the first place you need to size your overflow correctly to the return pump, going bigger isn't better for siphon overflows. You typically run return pumps at half there full scale rating with total head loss. This means if your return pump is rated at 1000GPH your overflow should be rated at 500GPH.
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