Hi Randy.
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If so, do most skimmers take them down below levels where the plenum is "effective"?
I agree with you that it depends on the specific context of what you want to know. If you're talking about eliminating nitrogenous nutrients, than no, a skimmer does not make this function ineffective, as the rate of nutrient utilization/elimination will balance with the nutrient load available to the bacteria, such is the case in any system, where everything down to the zooxanthellae populations utilizing ambient nitrogen for mitosis/population growth, etc, determines how much the bacteria get. However, with the Microcean system, personally, I consider it effective when it follows the course to the end product Prof. Jaubert originally got (and still gets in his completely closed experiments), high energy, oligotrophic, coral reef quality water; ie, levels of alkalinity, calcium, nitrogen that correspond with this description; all of these things being a direct or indirect function of the bacterial, bioturbation, and diffusion activity of the Jaubert sandbed and the "plenum" space underneath. When I discuss the use of skimmers, yes, I am referring to the removal of organic nutrients that can be handled ecologically by the system and its inhabitants; of which a portion (that which is not used in maintenance/growth of photosynthetic organisms, etc.) makes it to the end of the system, ie, nitrogen is utilized by the bacteria in the oxygen poor area of the sandbed gradient, thus, where these processes produce metabolic acids, thus breaking down the aragonitic sandbed to its components. Using a protein skimmer interferes with the above described consideration of "effectiveness" through eliminating organic material prior to its use ecologically, and thus, curbs the amount of bacterial metabolism, of which a high amount is necessary to keep calcium, alkalinty, etc. at adequate levels (ie, resonating those of coral reefs). re: the concentration of organics, this does not compromise the oligotrophic habits of high energy reef organisms, at least not in my experience, due to populations of mineralizing bacteria (along with other organisms that use organic compounds) expanding in the high oxygen area of the sandbed gradient to compensate for the increased load. The problem is, the skimmer is more efficient, in a function of time, than mineralizing bacteria. Thus, with a skimmer, you either never allow enough mineralizing bacteria population to even worry about efficiency (or you reduce populations by adding a skimmer later in the game), and, in the end, disallowing adequete levels of calcium, alk, etc. (Or you have to feed much much more than you would without a skimmer to achieve them, but this is very redundant, and I would consider it a potential danger based on the quirks of skimmer function I have dealt with in the past). Phosphorus is handled by use of densely stocking photosynthetic organisms into systems. Zooxanthellae have been underestimated for this capacity, and any manner of foraminiferans, and relatively natural population densities of algae (even though, in theory, a paradox is created by fueling growth of calcareous algae in respects to the system's need for the inherently enriching food to liberate calcium and carbonate, the rates of utilization and accretion are not relative direct reciprocals, so it works out in practice), rapidly growing microalgae, any algae/utilizing organisms in the sediment and in the system, as well as grazing animals keeping it in cycle, can handle phosphorus adequetly, in my experience. However, I enjoy a healthy biodiversity of algae, in that, while some species may produce alkaline phosphatase, and others may utilize mostly soluble reactive phosphate. As the pathways are numerous for phosphorous, so can be our methods of ecologically utilizing it in the reef aquarium.
Best,
Chris
[ September 08, 2001: Message edited by: galleon ]
