What are the dimensions of your tank? I have a 30" tall tank and the WPG really doesn't count for much, IMO the main thing to consider is the surface area and length. Plants will grow slow for me when I use 2 T8s, and 3 T8s will grow everything just fine for me. The main problem I ran into is plants shading each other out. My tank is only 18" wide, so I place a 4ft. T8 every 6" from front to back. T5s are a lot more efficient and usually have very nice reflectors! If I used T5s, I would only consider the spacing out of the lights based on how quickly I want everything to grow.
What are your goals with this awesome aquarium? Do you want moderate growth, or more on the high tech side? Do you like more of the difficult stem plants, or cryptocorynes? IMHO the 220gal number doesn't matter much, but length and spacing out of the lights does. Take a look at the large aquarium threads, it might help you get a feel for how plants grow under a certain amount of bulbs. Ask people who have large aquariums that appeal to you, they would be happy to share notes on what plants did fine, and what plants really needed the light levels higher to do well. This way you will know what to expect, and you won't have to buy more lights than what is needed to achieve your goals! Keep us updated, and document your build (and plenty of pics)!
