Ok I see.
You could get a canister filter, that would not hurt. However your money is spent on different upgrades first.
The set up is not bad. You just have to make a choice. You can stay with your current set up, and pour your heart and soul into a fully decorated low light tank. This means only java fern, java moss, anubias MAYBE crypts, etc. They grow really really slow in this set up, and it could take years to fully fill in. Also, if something goes wrong in the middle, you will have wasted a great deal of time. Nonetheless, if you took it really serious you could make something decent looking with your set up.
If you wanna have fast-growing plants like HC or Riccia, you definitely need much more light. You have about .75 WPG to 1 WPG right now I assume, and for plants like that you will need around 3.
One thing that has to be noted is that with this new intense wattage of light, you will need CO2 without a doubt. If you have 2-3 watt per gallon without CO2 algae will burst everywhere.
So, stay exactly where you are and buy low light plants, or upgrade to better lighting and a CO2 system and enjoy all the plants you want, getting the canister filter 3rd.