20 gallon long sump

I just picked up a 20 long for my sump for my 55 reef. I'm either going with reef octopus nwb 110 or bubble magus curve 5. The first chamber is going to be 10 inches long and the water level is going to 8 inches. Second chamber is going to be 12 inches long with a sump level of 8 inches. The final chamber is going to 7 inches and 6 inches deep. The reason why I'm keeping the water level if my pump stops and back siphons water even though the return line is going to be barley under water and have a hole just barley under the water as an anti siphon device. But if my ato goes haywire and dumps water into my tank. I'm going to use a Jbj ato and a aqua lifter pump. Is it possible to set it up so I have a float that senses when water gets to low and a switch that senses when water gets to high.

Thanks