[piercho]

Electric130: I'm using a 4" diameter CC skimmer per snailman's instructions. The total heigth is over 6' tall. My tank water level is 4'9" above the floor, I set the return at about 5' and drive enough air to generate the >1' foam head.

I'm currently using a 6" Rena Micro-Bubbler (Aquarium Pharmaceuticals) as a diffusor for this skimmer. The bubble size isn't as fine a basswood or limewood, but you get a lot of bubble surface area, so it's a trade-off. They are a bit spendy, i think around $6 each, but last a few months (6, or more).

Another option is KW's awesome air diffusor, a DIY diffusor. Snailman has directions on his website. You will need to buy a block of basswood (try eBay) and get it cut on a tool like a band saw to do this one. snail man says that this one will improve your foam head over using multiple air stones - that is, inject more and finer bubbles at lower backpressure. I haven't tied it.

One thing to consider before you undertake this is the air pump. Most diaphram air pumps sold for the hobby just won't, IMO, be able to produce a very good foam head heigth with a large, deep skimmer. I use part of the output of a Medo AC602 linear piston pump for mine. That pump could probably drive 2 skimmers the size of mine, or more. The air pump (or pumps!) needed to drive the skimmer will be the main cost of using a tall CC skimmer.