I bought a 200gl tank and didn't want to lose so much space with a hudson valve then I found this. We will only lose about a 1/2 inch of space from top of tank so we can get 190 of water in tank.
Pretty clever. I've had a couple of those liquid level floats for several years..still haven't gotten around to installing them. Originally I was going to use one to ground out the machine before the tank ran out of water.