| Lithaqua
Halimeda is a well-known tropical benthic genus of green algae. Fairley large, of centimeter to decimeter dimensions, species of this genus consist of strings of flattened or sometimes crinkled, calcified discs connected by flexible joints. They are abundant in shallow seas around the tropics especially on "coral"reefs and in their lagoons, although some species range down reef drop-offs to great depths. During the 1950's when large numbers of deep bore holes were drilled into Pacific atolls, geologists found that the dominant element of the carbonate structure of these atolls was not stoney coral but rather a lithified sand made up of the lobes of Halimeda. The members of this genus rank as one of the most important calcifiers of the biosphere; it is likely that their CaCO3 production over all tropical seas is considerably greater than that of the stoney corals.
Halimeda is a member of the green algal order of Siphonales. In breif, anatomically, members of this genus are constructed of tubules, with very few cross walls. Thus, individual cells are extremely long and narrow. At the surface of the discs or lobes, the "bat like"surface expression of these tubules (called utricles) is slightly swollen to form a continuous surface as a kind of cellular pavement. Just below the surface of the lobe, there are considerable spaces between the utricles. The calcification occurs almost entirely in these interutricular spaces. Thus, through the anatomy of their utricles, these algae provide one of the basic requirements for biomineralization, confined spaces in which critical supersaturation can occur.
When photosynthesis occurs rapidly, CO2 diffuses from the water immediately exterior to the plant and, particularly because this is the largest surface of each utricle, from the interutricular spaces. This strongly raises the pH and the concentration of carbonate ion in the interutricular spaces. As long as calcium is available to diffuse through the porous cell wall from the exterior, calcium carbonate becomes highly supersaturated in these largely enclosed spaces.
This information comes from a book called Dynamic Aquaria by Walter H. Adey from Marine systems laboratory National Museum of natural History and Karen Loveland, Smithsonian Institution.
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11-13-2005
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Modern multi-chamber filters, contain mainly plastic media. Those are excellent supports for bacteria but, they do not add anything to water quality. It is important to fill at least one filter chamber (preferably the last chamber) with Bacta-PurŪ LITHAQUA. It provides an enormous surface area for bacteria (10 to 20 times more than most plastic filter media) and provides the bacteria with essential nutrients. Bacta-PurŪ LITHAQUA neutralises acid pH and helps to restore carbonate alkalinity. It provides a natural environment, on which bacteria in Bacta-PurŪ KLEAR and Bacta-PurŪ Sludgebusters can grow. It is an essential aid to achieve a clear and healthy pond.
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