Just change the bulbs out; you don't need a new ballast for a different spectrum of bulb.
65w more with CF would land you with about 4.5wpg... excessive in my opinion. Unless you're leaving a hood on the tank, adding tannins, or some how interfering with the light in some other way, you'll be doing a good bit more work under much more rapidly changing conditions. Some people enjoy that, but it is challenging. My 20g runs without a hood and 65w of CF 6500k/10000k sunpaq bulb, and the HC is looking pretty good; it grows low.
For now, your plants aren't in water, so the light isn't diffused so heavily as it would be in water. I'd imagine more light now wouldn't serve much of a purpose; stick it in the window if it is, there's not much to fear from algae when there's no water. If you're having trouble keeping the HC from getting stringy in the future once the tank is filled, another strip more in the 15-30w range might help. You can use this one to play with aesthetics if you like, since you'll have an open range of choices between CF, T-8 and T-5.
-Philosophos