besides flourish excel...?

Add light would be my suggestion

I dont really see a point in adding excel to a tank with that low of a light. Up your lighting to atleast 2x the size of your tank and then worry about excel and other nutrients.

The lights at the link below are the same as what I just ordered for my 25 gallon. The 24" and 30" are 65w...which would put you just over 2 w/g. I would imagine these prices are pretty good. They are $20 cheaper then anything I could find at a LFS.

http://www.amazon.com/s/ref=nb_ss_misc?url=search-alias%3Dmisc&field-keywords=Coralife+Freshwater+Aqualight&x=17&y=16http://www.amazon.com/Coralife-Freshwater-Aqualight-Single-Linear/dp/B000BJM9A4

Check coralife for their freshwater strips. For a 65w you will run around $50-65 for it.
Can check bigalsonline.com thatfishplace.com or drfosters site (bigals will have bigger savings)

You can also go for T-5 setups but those are relatively more $$ but are favored greatly by those with high tech planted tanks.

Another option is ahsupply.com

Coralife 65w is perfect and not to expensive.

Umm rundown of lighting.

As guideline people use watts per gallon to determine how much light to get.
low light 2wpg and below, above 2 medium, above 3 high.

Wpg is important because certain plants need more light then others for photosynthesis. Low light plants vs. High Light plants.

The spectrum of the bulb will determine the color of the light. a 10,000k bulb will be a crisp white and 2500k will be a very yellow. Most plant bulbs will be 65k or 55k which is closest to the color of the sun. You wanna stay in a range of 55k-10k.

Good places to buy hoods/bulbs
Hellolights.com
Bigalsonline.com
Ashsupply.com(cheap diy hoods)