I find this part of the Tropica article interesting:
" Starting with the nutrients, an average plant aquarium with a decent fish population usually has sufficient nitrogen and phosphorus. When it comes to iron, potassium, manganese and other micronutrients it is often a trickier thing. Some aquaria are well planned from the beginning with, for example, laterite and other fertilizers in the substrate whereas others are not. In most cases, however, an aquarium plant fertilizer without nitrogen and phosphorus may safely be added to maintain healthy growth. It is often a much more difficult and expensive task to provide adequate light over the plant aquarium. Both fluorescent light and highpressure-quicksilver lamps may produce sufficient light if supplied with effective reflectors but in deep aquaria (more than 50 cm) is very difficult to offer enough light to small light demanding foreground plants. Based on our experiments, we suggest commencing CO2 addition before any other action is taken! We believe that even at very modest light intensities you will experience a conspicuous change in plant performance in your aquarium. The exact amount CO2 may always be discussed but if you do not have very sensitive fishes in your fish stock, concentrations from 25 and up to 50 mg/l will only improve plant growth. You will probably see that plants, which were barely able to survive before now, thrive in the presence of CO2."
Am I wrong or does is it say that there are usually sufficient levels of N and P in the typical planted tank without the need for supplementation and that light, CO2 and micros are the areas that need more attention?