Limiting nutrients was the dominant theory 15 or 20 years ago. The culmination of this was the Sears-Conlin paper (which advocated full fertilization, excluding phosphate). When Tom Barr started promoting the idea of providing all the nutrients plants needed. Limitation theory was abandoned by just about everyone. The reason it was discarded so quickly by most was that limiting plant nutrients just doesn't work. Been there, done that, and I'm not going back. Phosphate is a required nutrient for every form of life, and while it's relatively easy to starve plants, being larger organisms with higher levels of demand. Its next to impossible to starve algae, which is the dominant form of plant life in hostile environments. Three things are involved with a successful planted tank, imo. (These are in no particular order).
1. Light, to drive photosynthesis. Not many people miss this.
2. Nutrients, enough to support the rate of growth (determined by the amount of light applied). Nutrients include carbon, macros and micros. People forget that in a fish tank these are always available at high enough levels to sustain an algae bloom, but may not be high enough to sustain growth of "higher" plants. Given the correct balance between fish load, and a nutrient rich substrate, some will never have to fertilize. The thing is, active management of nutrient levels ensures that nothing is ever going to run low.
3. Lastly, plants should be dominant in the system. High levels of plant growth in a tank precludes excessive algae growth. Not sure of all the mechanisms in play, though all the evidence points to the fact it has nothing to do with competition for nutrients. Fast growers are an easy fix for this problem. I have success with tanks with floating plants, these seem to prevent a lot of the algae that can accumulate on slow growth leaves, even at low light levels.
Hope this helps
