Undercurrent DWC build. Air/Water pump, and tubing sizing questions.

I plan to build a 4 bucket undercurrent DWC system. My tent 4.5ft x 3.5ft so space is limited. I was thinking...

5 gal buckets
5 gal control bucket with a float valve to res
What diameter PVC? (thinking 2" pvc)
What diameter return? (thinking 3/4" rubber tubing)
What gph water pump?
What size air pump?
Best grow medium?
Size of net pots?


Heres a link of what i basically want to build...http://cch2o.com/index.php?main_page=product_info&cPath=31&products_id=10


Thanks for the help !! Please only post if you have experience !!

Hey, just wondering how it coming along? I have just finished my 12 site DWC. I used 6-5gal buckets on one side, and went with 3-37gal +/- with 2 sites per tote on the other. I have a 1000watt hps servicing one side, and 2-600watt on the other side. This is my first attempt at a multiple site DWC as well. Hope you found something. Here is mine as of now, let me know.
[video=youtube;mlW12YwFtCc]http://www.youtube.com/watch?v=mlW12YwFtCc[/video]

I think you need to run the 2" all the way back to the res,I made a similar set up here is what I found out by trial and error,I wanted to run 6 buckets with 2 rows of 3,so I got some 1/2" tubeing and ran it from my res(18 gal tote)to my first bucket and then conected them all togeather,the line was to small to move to the next bucket and the first bucket filled to the top,so I got some 1" tubeing and ran that from the out line to the rest of the buckets so what I have is a 1/2" feed line with 1" and 1/2" lines to the rest of the buckets and back to the res. I use a 400 gph pump with a ball valve to control the flow,now the level stays the same in all the buckets and it is circulating back to the res,if you were to run 2" I think you would have good flow and you can use a ball valve to control the flow,I use 5" net pots and lots of air,I have a very large air pump theres no specs. on it but I got it from a friend that sells live bait for fishing and had it laying around,the problem with building your own set up is the trial and error part of it cuz error usually means more money and I can tell you I got quite a few dollars invested in a few differant set ups I built over the years but it was fun. good luck