Dosing from a Co2 Cylinder is the way to go. If you can't afford a CO2 setup, check out this link:
http://www.aquaticreefsystems.com/autocheck_valve.htm

For cheap plant, there's ton of plant in the San Marcos River. Peoples said not to use it b/c of bacteria, disease, contamination. The Texas Cichlid live in the San Marcos River if you can catch them.

It's recommended that you change water and prune the plant as much as possible.