After all these years, it turns out that the nitrifying bacteria are not what we thought.

Biological filtration is the critical filtration component in every aquarium. Whether the biological filter is live rock, trickle media, a sponge or any other substrate, the oxidation of ammonia to nitrite and then to nitrate is necessary to keep these substances from reaching toxic concentrations in our aquariums. It has been a basic tenent in biology and the aquarium hobby that there are two bacteria responsible for nitrification. The first, called Nitrosomonas europaea, oxidizes ammonia to nitrite, while the second, Nitrobacter winogradskyi, oxidizes nitrite to nitrate.

FAMILY: CLAVULARIIDAE

The terms, Star Polyps and Clavularia may be rather unfamiliar to many marine aquarists but all marinists interested in invertebrates will have come across the many species of the these delightful colonies, if they do not already own one or two. Unfortunately, the family Clavulariidae, commonly known as Star Polyps, has long been confused with Xenia to which it superficially resembles; so much so, that it has, quite wrongly, been labelled Xenia with gay abandon and little regard for correct scientific terminology. To put the record straight, Xenia are Pulse Corals with polyps held on elongated stems, unable to withdraw into a basal mass. On the whole, they are far more sensitive than the clavularids and usually require optimum water and lighting conditions. Star Polyps, on the other hand, are not a difficult coral to keep and often make an ideal choice for the newcomer to invertebrates.