Water Bridge?
 

I want to link to tanks and Want to know how to make a water bridge?

Here's a link:

http://www.bio-elite.com/waterbridge.htm

I don't think the guy who did it stresses this enough: both tanks have to be at the exact same height! If not, you'll get a nasty flood until both waterlines are even. I also think this idea would work best with two tanks of the same size. I also don't think it would be nearly as good of an idea without the canister filter connecting the two tanks, as this forces water flow through the bridge.

thank you that answers it all