It’s hard not to pass up a good deal, whether it be on aquarium livestock or equipment. We’ve already commented on why it’s a bad idea to purchase livestock on the fly without researching fish or corals first, but doing this with equipment can be just as bad. If you spot a supplement you don’t normally use, don’t just buy it because it is on sale. There is no telling what kind of additives are mixed in with that supplement, and after some dosing, you may find out the hard way just how bad things can get. If not a supplement, aquarium equipment choices need to be carefully made so as to avoid wasting money and buying incompatible products. Fortunately, most equipment purchases can be returned, but this isn’t always the case and you may be stuck with something you don’t want or can’t use.