Can you OVER-skim?

[Dale]

I will take the opposing view and say YES you can definately overskim. So there
To answer the question properly you have to consider the livestock being kept.
The question is relative to the proposed inhabitants of the tank. There is no "one size fits all" approach. Most people who subscribe to aggressive skimming keep SPS corals primarily. They rely on high intensity lighting for photosynthesis and want to avoid any free nutrients as a possible food source for algae (which SPS cannot defend against).
However, if you are considering a softie tank, or clams and other filter feeders, overskimming will most definately lead to starvation. Many of these organisms thrive in nutrient rich waters.
Trying to mix SPS, softies and clams/filter feeders can be a difficult and/or expensive proposition. You either have a naturally nutrient rich tank (and battle the occasional algae outbreak on SPS) or you overskim, constantly dose nutrients for the others and then just skim them right back out again.