If your going to put it over your 30 gallon tank i would suggest a 3 foot dual light fixture(i.e. shop light)...that will give you 60 watts of lighting and 2 watts per gallon which is more than enough to grow a wide variety of plants. Look around at home depot, or lowes, you should be able to pick a fixture up for under 10 bucks and the lights are 5-7 bucks each. You can go this way for pretty cheap(probably no more than 25 dollars and then either make or buy a hood) or, you can go the more expensive route and get power compacts...they are nice, but the bulbs are quite expesive as are the fixtures.