[BoomerD]

Most of us believe that that myriad of pretty colored bottles on the shelf at the LFS should stay there, because they are designed to separate you from your hard earned fishy-$$ more than anything else. Other than calcium/alkalinity buffers, you shouldn't need to supplement ANYTHING in your tank (well, PERHAPS magnesium, but only after you test) and you should NEVER dose anything that you don't or can't test for. If you don't test for it, how do you know how much your tank needs? Just using the manufacturer's recommendation will make them lots of money, but could throw your tank's water chemistry out of whack, and some are toxic in elevated amounts. Like Witty says, water changes SHOULD take care of all the necessary elements your tank needs, AND, water changes are one of the most healthy things you can do for your tank...