Originally Posted by Austin
Are the nutrients toxic to the fish? Like, should I bother vacuuming the unplanted areas?
In normal amounts, no. Everything goes back to balance. An aquarium, planted or non-planted, that is "balanced" will be healthy with regular maintenance. "Balanced" means the fish load is not beyond what the natural processes can handle in that volume of water, substrate, etc. Problems occur when this balance is out, usually due to too many fish for the tank's capacity, and/or insufficient maintenance for the fish/water ratio.
As for your second question, that also depends upon the balance. In some of my tanks I do, in some I don't.