When first setting up an aquarium, levels of uptake and decomposition are low. As live rock "cycles," and dead plants and animals decompose, a nutrient spike is seen in all cases. Following this, various algal successions occur, usually in the order of diatoms, cyanobacteria, filamentous algae, and finally crustose coralline algae. Nutrient levels drop over time and the reef becomes a stable low nutrient place. The same process is occurring with increasing food sources to an aquarium. The nutrient levels spike, and various algal successions occur, until a new steady state is reached with a larger number and diversity of life than at the previous level. This process can take time, and food can be slowly increased over longer periods of time, allowing for such development to occur and bring measurable nutrient levels down to previous water column levels.
It is my experience that perfectly "obscene" levels of food can be added to well stocked and diverse reef aquariums over time without high nutrient levels in the water column. To be sure, algae growth will also increase even over the long term with the added nutrient inputs, even though measurable levels are low. This is easily countered with the addition of more herbivores. Grazing has been shown to be the primary means of both filamentous and fleshy algae control on reefs.