mojoreef
Just a reefer
Ok folks here is round one. This is the discription and concept of a Jaubert Plenum. Take a pick and let go from here.
Professor Jean Jaubert, originally of the University of Nice, in France, was the originator of this sytem to be used as a nitrifier and a denitrifier using bacteria in both areobic and anaerobic states. Prof. Jaubert also determined through closed system experimentation that the key to unlocking the potential to the sediment was diffusion. His discovery began to materialize in the late 70's, and reached an apex in the 90's with an American patent (which was obtained subsequent to his European patents of the same system), # 4,995,980 (Delbeek, 1994).
Moving on to a correct setup and utilization of the system, an understanding of nitrogen utilizing bacteria is required. As many aquarists are familiar with the nitrogen cycle in aquaria, and that upper layers of sediment are excellent for aerobic nitrogen breakdown/utilization, they also realize that for nitrate to be effectively utilized by the bacteria (and converted to nitrogen gas), a substantial surface area of space that is low in oxygen (generally below 2 mg/L) needs to be present. Well, deeper sediments provide an ideal area for nitrate breakdown and utilization by bacteria. Thus, the Jaubert system, consists of a 4"-6" deep layer of sediment having mass resonant of that found on high energy reefs (i.e., variable sizes, with little to none smaller than 2 millimeters, Carib-Sea's Geo Marine Crushed Coral generally makes the ideal substrate, along with some large grains mixed in), which rests on top of an elevated diffusing plate (usually plastic lighting louvre/eggcrate covered with fiberglass screen to prevent sediment from falling through). The sandbed/diffusion plate rests 1"-2" above the bottom of the container/aquarium, supported by small sections of one or two inch PVC pipe.
It is important to keep the sides (below the sand line) and underneath of aquarium covered to prevent any light from entering the sandbed/plenum system itself beyond what comes through the exposed topside. Keeping all light from the sandbed and "plenum" space system prevents extra growth of oxygen producing autotrophs in the space meant for low-oxygen, nitrate utilizing bacteria. This assists in maintaining the oxygen concentrations in the plenum space at around an optimal 1-1.5 mg/L,. Some oxygen should be present in the plenum/lower sandbed, as just mentioned, in order to prevent hydrogen sulfide buildup, etc.. This small allowance of oxygen is provided through bioturbation by absolutely pivotal sanded infauna. These infauna also allow diffusion of nitrogen gas back up through the sandbed to escape the system.
Once established, bacterial metabolism produces organic acids and bacterial respiration forms carbonic acid in the local water. These processes/substances lower the pH of the sandbed and allow dissolution of the argonite substrate, with diffusion assistance from the plenum space below. The ions liberated by these actions are diffused in the display/bulk water via the same bioturbation that allows nitrogen to escape. These ions and their functions in terms of scleractinian corals and maintenance of reef-quality water. The trick to gauging the amount of ions liberated and the demand for their maintenance of water quality lies in initially monitoring the carbon/nitrogen/food input of your system, and testing for the ions and their rates of depletion. Also, sandbed area has to be large enough to be able to completely utilize nitrogenous nutrients in order to maintain oligotrophic (nutrient poor) conditions. It should also go without saying that high energies above the sandbed and light resonant of levels found on natural reefs are integral (of course, "resonant" referring to "as close as possible by a hobbyist/aquarist").
Ok thiers a start.
MIke
Professor Jean Jaubert, originally of the University of Nice, in France, was the originator of this sytem to be used as a nitrifier and a denitrifier using bacteria in both areobic and anaerobic states. Prof. Jaubert also determined through closed system experimentation that the key to unlocking the potential to the sediment was diffusion. His discovery began to materialize in the late 70's, and reached an apex in the 90's with an American patent (which was obtained subsequent to his European patents of the same system), # 4,995,980 (Delbeek, 1994).
Moving on to a correct setup and utilization of the system, an understanding of nitrogen utilizing bacteria is required. As many aquarists are familiar with the nitrogen cycle in aquaria, and that upper layers of sediment are excellent for aerobic nitrogen breakdown/utilization, they also realize that for nitrate to be effectively utilized by the bacteria (and converted to nitrogen gas), a substantial surface area of space that is low in oxygen (generally below 2 mg/L) needs to be present. Well, deeper sediments provide an ideal area for nitrate breakdown and utilization by bacteria. Thus, the Jaubert system, consists of a 4"-6" deep layer of sediment having mass resonant of that found on high energy reefs (i.e., variable sizes, with little to none smaller than 2 millimeters, Carib-Sea's Geo Marine Crushed Coral generally makes the ideal substrate, along with some large grains mixed in), which rests on top of an elevated diffusing plate (usually plastic lighting louvre/eggcrate covered with fiberglass screen to prevent sediment from falling through). The sandbed/diffusion plate rests 1"-2" above the bottom of the container/aquarium, supported by small sections of one or two inch PVC pipe.
It is important to keep the sides (below the sand line) and underneath of aquarium covered to prevent any light from entering the sandbed/plenum system itself beyond what comes through the exposed topside. Keeping all light from the sandbed and "plenum" space system prevents extra growth of oxygen producing autotrophs in the space meant for low-oxygen, nitrate utilizing bacteria. This assists in maintaining the oxygen concentrations in the plenum space at around an optimal 1-1.5 mg/L,. Some oxygen should be present in the plenum/lower sandbed, as just mentioned, in order to prevent hydrogen sulfide buildup, etc.. This small allowance of oxygen is provided through bioturbation by absolutely pivotal sanded infauna. These infauna also allow diffusion of nitrogen gas back up through the sandbed to escape the system.
Once established, bacterial metabolism produces organic acids and bacterial respiration forms carbonic acid in the local water. These processes/substances lower the pH of the sandbed and allow dissolution of the argonite substrate, with diffusion assistance from the plenum space below. The ions liberated by these actions are diffused in the display/bulk water via the same bioturbation that allows nitrogen to escape. These ions and their functions in terms of scleractinian corals and maintenance of reef-quality water. The trick to gauging the amount of ions liberated and the demand for their maintenance of water quality lies in initially monitoring the carbon/nitrogen/food input of your system, and testing for the ions and their rates of depletion. Also, sandbed area has to be large enough to be able to completely utilize nitrogenous nutrients in order to maintain oligotrophic (nutrient poor) conditions. It should also go without saying that high energies above the sandbed and light resonant of levels found on natural reefs are integral (of course, "resonant" referring to "as close as possible by a hobbyist/aquarist").
Ok thiers a start.
MIke
