Id agree with you...
I try to make sure I have atleast 1.5 watts per gallon for low/medium light planted tanks and 2 - 2.5 watts per gallong for medium/hugh light planted tanks.
Youll probabably grow some good algae though....
I had 98 Watts on a 100G tank and struggled to get my plants going. Seemed the algae outcompeted them at every turn. When I bumped it up to 172 (4x39w T5, 2x 8W T%) things picked up almost immediately.
I would have used more, but its a corner tank so its a pain to fit lighting to it.
That being said, how much light you want depends on a few things. How deep is your tank? 220G is alot of water, and depth has a huge impact on how much light reaches the plants.
What are the dimensions of your tank?
other things I would watch are the colour spectrum of the tubes you are using and what the light needs of your plants are.
theres some pretty good posts on here that i dig up form time to time.