Those work if your RO/DI had the preseasure switch, also, just know (research) that they are prone to fail. BRS sells this that shuts off the water if it detects water, I have it and it's great, but doesn't get the water from your fresh water tank to the sump. It's also after the fact - so for me, it's the last and 3rd line of defense against a flood http://www.bulkreefsupply.com/store...eak-controller-detector-for-ro-di-system.html
That is what I use with a Tom aquarium aqua lifter pump. The fail safe float is a MUST have. Electronic floats WILL fail eventually and it would be worth the $10 extra bucks to save you from a flood.