I used to buy plants, only to have them dissolve and die off in my 120L
tank. Better lighting and flourish excel, combined with a better choice
of plants bought on-line has worked wonders. Algae (which I didn't
really have a problem with to begin) has all but disappeared. I do a 15%
change every week, skipping one in every four weeks. Fewer water changes
are better for plants, worse for fish. It's all about finding the
balance that works for your setup. I dose with flourish 3 times weekly.

HTH,
Rob.