I agree with you and legomaniac89. You have a lot of light for a 30 gallon tank. Reducing it to 2-3 bulbs (you can actually apply the WPG guideline here, since you are using T12 bulbs) would give you enough light to grow many plants (including high light requiring plants).I feel I have WAY to much light for this tank. I was thinking about upgrading to a 55g to lower the WPG to 2.9, but what do I know!! This is my first attempt at trying to plant a tank!!
Definitely decrease the amount of lighting somehow. Or you could get a bigger tank. With 160 watts over a 55g, you'd still be able to grow anything.So my question is, if you had this set up, what would you do? Change anything? Leave the WPG, lower the WPG? What kind of plants will grow?
Also as legomaniac89, I would avoid DIY CO2 if you intend to have a high light planted setup. This is because in high light, CO2 becomes a requirement, and fluctuating levels of CO2 will lead to severe algae problems (combined with high light, of course).
In addition, with so much light, you will need to fertilize (both your micro and macronutrients). Again, as legomaniac89 mentioned, the dry chemical route is cheaper and economical in the long run, but commercially available fertilizers will also work.