I already have the other skimmer too and I may as well use it. If I don't get all this going before it starts to warm up I may just shut off the other one.
Rory, The tank is just a standard 20 gal from Bow Valley, I have access to a proper low RPM drill and the hole saws so I'm just going to do it myself.
On a 16 I doubt the bottom is tempered as it would need to be cut to shape, then cooked. Only way to know for sure is to ask the company that built it or look at it through polarazied lenses, if it it tempered you should see waves in the glass.
I hadn't thought about an external pump for some reason, I already have the return but there is no reason I couldn't get a mag or something. I'll probably try it with the one I have now first but good idea.
For head loss and etc, I should get 350 - 400 g/h considering rise and elbows, at the SCWD, that is going to cost me a bit of head there but according to the table I found at Marine Depot (
http://www.marinedepot.com/md_viewIt...product=3Q1111) I should be getting between 250 and 350 to the tank. As long as I hit 250 I think I'll be happy, I can add a seio for extra flow if I need to.