Berlin skimmer Mods? Is there any?
 

I'll be running a Berlin "Triple Pass" Skimmer for a while on my 150g tank. It came with the tank, and can't afford a "Nice" one. I will be feeding it with a Mag 7. The air injector, is on the outlet of the pump. I see alot of "mesh Mods" for other pumps. Would putting the air injector before the pump and some kind of mesh on the impeller work better for smaller bubbles?

Your modifications should work as planned. You may not need a mesh mod, either... try it without modifications to the impeller first, and then if you want finer bubbles work your way up. I did a 'web wheel' mod to the impeller of my RV pump and it produces some fine bubbles indeed, and it is reversible (you just take the fishing line off)...
http://i633.photobucket.com/albums/u...rity/013-2.jpg

You could try something like this before you permanently mod the impeller on the Mag 7.