Additives includes any thing added to the tank in order to counteract the depletion by physical, chemical or biological processes. There is a vast array of additives on the market, however, the majority of these are not only unnecessary but could prove toxic to the tank. At the very least they are a waste of money.

Before adding anything to the tank, an aquarists should consider the following questions:

• Is the additive required by any organisms in the tank?
• Can I measure the levels of the substance in the tank and determine if addition is really necessary?
• Is the additive toxic at high concentrations?

Last updated: November 2, 2004