The algae is more than likely being caused by a nutrient imbalance, especially since you aren't dosing any ferts. A phosphate test kit is very important for a planted tank, and essential once you go high light. I would recommend picking up one now as it will make getting your tank back in balance much easier.
I would recommend picking up the following ferts from
www.GregWatson.com.
CSM+B Plantex (Trace Mix)
KNO3 (Nitrates and some Potassium)
KH2PO4 (Phosphates)
K2SO4 (Potassium)
For the size tank you have these will be the most economical way to dose ferts in your tank. I suspect that once you start dosing Phosphates and Potassium, your Nitrate usage will increase significantly. You want to maintain a 10-20ppm Nitrate to 1ppm Phosphate ratio, and Potassium should be dosed at least 10ppm twice a week.
Once you get your ferts in balance, it will be easier to tell wether or not CO2 is a necessity with the amount of light over your tank. It would definately be beneficial and make fighting algae much simpler.
Surprisingly enough many people report that it is much easier to take care of a High light tank than a Medium Light tank. Probably in large part due to people trying to treat them like low light tanks, when the care needed may be closer to having a high light tank.
If you want to make things easier for yourself without plunging into high light, I would suggest either cutting back to one bulb or replacing one of the two bulbs with a 50/50 bulb. This would still give you enough light for plants but would make your tank more low light and easier to care for. Especially since all the plants you have listed as being in your tank will do well in low light.
You probably wouldn't need to get CO2 levels as high for a medium light tank, but you would want to make sure that they were consistant. This would be extremely difficult to achieve with DIY CO2 especially on that size tank. I would probably be easier to use Excel, but also could get expensive rather quickly.
There are shrimp, snails, and fish that eat algae. Most will only help keep a mild outbreak in check. If you are going to use them you should still try to get your nutrient levels balanced, otherwise the algae may become so bad that they can't keep up.