After suffering with inferior protein skimmers for many years... I finally found a good deal on one with potential. The original pumps that came with the skimmer had already died so I bought the skimmer body only. After seeing the awesome performance of recirculating skimmers and beckett injected skimmers, I dedided to make a dual beckett-injeced recirculating skimmer from my pumpless Euroreef 12-1. That's right, it's 12" in diameter.
I bought a 1 3/4" hole saw from Lowe's and drilled 3 holes. The uniseals are from Aquatic Ecosystems and are for 1" pipe. I was nervous about cracking the skimmer if the hole saw "bound up" too hard, but the drilling was easier than I'd expected (I went slow with very little pressure). The uniseals fit beautifully in the holes but it takes quite a bit of force and spit to get the pipes through the uniseals. Maybe a 1/16" bigger hole would have been an easier fit. I haven't tested it yet but I have high hopes.
The DIY beckett injectors are fairly easy to build too. There was a thread on reefcentral with step by step photos but I think it was lost in the server crash. I hope this is helpful to anyone who's been thinking about a "recirc mod" for themselves.