I think your problem is in the lighting although I'm definitely not even close to being an expert. 20 watts over a 33 gallon just isn't going to grow anything. What I would do is just get a glass canopy and a standard home depot light fixture which you would hang over the tank. Then, just get some good plant bulbs (I would aim for 2-3 watts per gallon and if you can't find that in a one bulb fixture, then get 2 or 3). And I agree with what has been said about the 80 gallon tank. It will cost you a lot, so get it sorted out first in the 33, then aim for the 80.