This update is primarily dealing filtration and nitrate control and has multiple changes/corrections in sections dealing with this. Marine/Saltwater Aquarium
I updated a Fish as Pets <http://www.fish-as-pets.com/> article with much more information and more outside references as well to provide better information
I updated the Aquarium Chemistry article, in particular the overview & section about GH with suggestions about the use of "dripping" positive mineral ion