I was going to make my 2.5G a pico but now I want to make a 10G my SW and have the 2.5 as a refuge. But how does one do it? would I need to have a powerhead or something I know its prob easy to do but I just dont see it 

If you make the top of the tanks level, you can run two pipes between them. One is the siphon to return water, and the other has a powerhead hooked to it to push the water over. I had a setup like this for 2 months no problems. Only broke it down because I am upgrading to a 90gal with sump below.
![]()