autotopoff.com?

They are awesome units and they have excellent customer service, with that said if you know a little about electronics or relays more specifically these units are very easy to build.

I have built a couple using a float switch from ebay, a radio shack $7 relay, and a few wires.

If your not into DIY i would recommend autotopoff.com, I have one of their double floats and it has never failed me.

Knock on wood.

 

They sell a great product i highly recommend them. I havea double float unit that has been going strong for well over 2 years with no problem! I would recommend the double float version just as a back in case the first float fails.

 

What they said!

 

I have three of their units. Work flawlessly.

 

+1awesome stuff!

 

I would suggest looking into Tunze Osmolator.  It's about twice as much as a double from autotopoff.com, but it also comes with a pump and has two different water level detection systems which reduces the chances of failure.  Tunze has great products.  BRS has a good little video tutorial about them that might be helpful http://www.bulkreefsupply.com/store/video?file_name=174
Buying a good ATO is important investment because you can flood your house!