I'm purchasing a pre-setup float valve hooked up to a small extension cord. I don't know if I can post the web address here so you'll have to email me for it if interested (just to be safe). It's rated to have a 1/4" sensitivity but people using this same switch say its more sensitive than that.
You plug an air pump into the extenstion cord.
You drill two small holes in the top of a container (I'm thinking of using a 1g jug w/ screw on top) just enough to get the air line in there snug make sure its air tight (seal w/ silicone, make sure the cap is air tight a test run will tell you).
Instert two pieces of air line tubing in the holes w/ at least one going to the bottom of the container.
Hook the air pump up to the one that dosen't have to go to the bottom.
As the float switch turns the air pump on it will pump air into the container and the water will exit through the other piece of air line tubing into the tank via the building pressure because the 2nd air line is the only escape (importance of making everything else air tight). Once the float switch rises enough it will shut off the air pump.
This is in no way my idea, I took somone elses DIY post and on a "large" nano and shrunk it a little. I would also recommend you put a plastic linking valve on both pieces of airline tubing near the cap for easy disconect and maintenance. And a couple of one-way valves.
Nudibranch@luckyreef.com