I have made several of these for folks online and just thought I would offer some of the extra ones I have to anyone on thereeftank.com.
Basically, The unit is an Acrylic bracket with two adjustable liquid level float switches. The switch on the bottom handles daily freshwater top-offs in tandem with the top
float switch which acts as a failsafe in case the bottom switch ever sticks on for some reason. In this case, your top-off pump would stay on only as long as it takes for the water level to rise to the second, failsafe, switch on the top.
I'm selling the one's I have left for 35.00 + 5.00 S/H
I still also have some single float switch setups for 25.00 + 5.00 S/H
This is my first post on this site, but if you do a search on Reef Central for my username you'll see good feedback.
Thanks, Matt.