Now, not to change the subject, but I have yet to see a conclusive argument that charcoal is bad for planted tanks. I e-mailed marinland and asked them about their product and they didn't have any concerns. Do you have any other good articles written about it?
"The reasons given for not using carbon or not using it continuously include: the carbon causes some diseases, it removes beneficial elements/substances for the water, and eventually the carbon will de-adsorb everything killing the tank inhabitants. None of these reasons have ever been supported by experiments or tests. Rather, they are myths. And as myths, they circulate through the hobby growing a life of their own which becomes hard to kill."
"In any case, whether a minor or trace element, most can have different chemical forms in water and not every form can be adsorbed by carbon (in fact most cannot). The form depends upon the pH of the water. It turns out that for most elements, the chemical form that carbon can remove is only present when the water pH is either below 3 or above 10. These are hardly pH conditions found in an aquarium. "
However, it also said this:
"Sometimes putting fresh carbon in your aquarium can raise the pH as the carbon can adsorb carbon dioxide and change other characteristics depending upon the water chemistry of the aquarium water and the type of carbon. Usually the pH change is temporary, but how long depends upon the alkalinity of your water. To minimize this, it is best to rinse the carbon under tap water for a minute before placing it in your tank. This will reduce the magnitude of any changes."