Mag 18 to use just to drain the tank ?
Quite an expensive way to go. Just get any cheap submersible pump. Does not even have to be that powerful. I use a no-name pond pump rated @ 300gph to drain and pump the water back.
Agree. For just draining purposes, go cheap. Here's what I use for my two 29gal on the second floor:
I cut the hose about a foot at one end and wedge it really firmly into the output (its actually in there super tight). When I do the w/c, I just screw on the other section of hose and drain into the my bath tub. Then to refill, I put the pump section into a 5gal bucket, fill the bucket up in the tub, and run the other end of the hose into the tanks. I only do it this way because I can't utilize a python type system on my second floor fixtures. The pump pictured is rated at 700gph and cost me well under $30 and its been working just fine for nearly a year now
http://www.ebay.com/itm/710-GPH-Sub...rhead-Fountain-Water-Hydroponic-/251163129225