fig1 and 3 depict the form of the invention integral to an aquarium . the filtration system is formed at one end of the aquarium by the wall ( 23 ) which extends the full width and height of the aquarium . as shown in the elevation and plan figures , the filter system is separated into three functional elements by the transverse walls ( 21 ) and ( 22 ). the area formed by wall ( 22 ) and the exterior aquarium wall is the anaerobic chamber . the area between the two wall ( 21 ) and ( 22 ) is the aerobic chamber and the remaining area between wall ( 21 ) and the exterior aquarium wall is the pumping chamber . the wall ( 22 ) extends from the bottom of the filter section to a point near to but below the intended level of water in the aquarium ( 10 ). the wall ( 21 ) in turn extends downwardly from the top of the aquarium wall , past the top of wall ( 22 ) to a point below the top of secondary anaerobic filter ( 8 ). resting on the top of wall ( 22 ) and extending to meet pendant wall ( 21 ) is the dispersion plate ( 2 ). dispersion plate ( 2 ) is pierced by a number of holes , sized and configured as noted below . water from the main aquarium enters the filter unit through an opening formed near the bottom of wall ( 23 ) in the area of the anaerobic chamber . water will first rise through a pre - filter ( 6 ) and into an anaerobic filter foam block ( 7 ). water will tend to continue rising until the water level in the anaerobic meets the tank water level ( 10 ). if chemical filtering is required it can be inserted at the top of the anaerobic block ( 7 ). the steady state water level will rise above the dispersion plate ( 2 ) and commence to trickle through said plate and on to the aerobic filter element ( 9 ). water will trickle through the aerobic filter ( 9 ) and into a secondary anaerobic filter block ( 8 ). water will pass out of the secondary anaerobic filter block into the bottom of the pumping chamber where it will be returned to the top of the aquarium by submersible pump ( 4 ) through the tube ( 3 ) and outlet elbow ( 5 ). looking in detail at the filter operation , water entering input port ( 1 ) from the tank is pulled in near the bottom of the tank where debris tends to collect ( uneaten food , solid fish waste , dead plants , etc .) these debris are trapped in pre - filter ( 6 ) where they decompose . if pre - filter ( 6 ) become clogged , it is easily removed by first removing anaerobic filter ( 7 ) and then lifting out filter ( 6 ). it can then be rinsed in tap water and returned to the filter . after the water has deposited the debris in pre - filter ( 6 ) oxygen starved water travels through anaerobic filter foam block ( 7 ) in a direction parallel to the long axis of the element . due to the fact that water is percolating upward through the foam block it will tend to use the entire area of the block rather than the opposite configuration where water is deposited on top of a block and tends to penetrate directly without dispersion . this makes for more efficient filtering . water now rises to the level ( 10 ) in the aquarium and covers the dispersion plate . the dispersion plate is so constructed that the water passing through the openings in said plate drips down the length of the aerobic filter element ( 9 ). the trickling action associated with the passage of water through the dispersion plate will aid in the absorption of oxygen and the release of nitrogen gas . oxygen laden water now trickles through the aerobic filter medium where aerobic microbe colonies remove harmful ammonia from the water and convert them to less harmful nitrites . fig4 and 5 are respectively plan and elevation views of the aerobic filter . the unique design of the aerobic filter medium enables high biological mass and density in a relatively small area . the aerobic cylinder consists of a central core of coarse perlon ™ or monofilament fiber material surrounded by a cylindrical frame of dls ™ or nylon screen material . air easily passes through the cylinder as water trickles through it allowing sufficient oxygen for aerobic colonies to exist in quantity . after passing through the aerobic filter element the water will pass through the secondary anaerobic filter element ( 8 ). this element may contain both aerobic and anaerobic bacterial colonies and performs the secondary function of supporting the aerobic filter element ( 9 ) clear of water . after transiting the secondary anaerobic filter , water passes into the pumping chamber and to the submersible pump ( 4 ) where it will be pumped through tube ( 3 ) and outlet elbow ( 5 ) back into the aquarium either directly or through an added spray bar . the action of the water return serves to agitate the surface of the water in the aquarium portion to increase the effective surface area . the action of circulating water in the aquarium by drawing water through an input port near the bottom and returning it to the surface will aid in eliminating dead spots of uncirculated water . the openings in the dispersion plate ( 2 ) are cooperatively sized with the capacity of the submersible pump ( 4 ), which may also be adjustable , to initially maintain the water level in the pumping chamber at or slightly above the top of the secondary anaerobic filter element ( 8 ). the length of the pendant dividing wall ( 21 ) is sized to reach a point slightly below the top of the anaerobic block ( 8 ). this effectively forces the water which has passed through dispersion plate ( 2 ) and the aerobic filter ( 9 ) into said secondary anaerobic filter . in ordinary aquarium use the total volume of water will gradually decrease due to evaporation . such a decrease in water volume will result in a gradual lowering of the water level at the secondary anaerobic filter element ( 8 ) and the submersible pump ( 4 ). the lowering of the water level will cause a portion of said anaerobic element to go aerobic . this effect will be reversed when the aquarium water is replenished . in use it has appeared that this periodic change in water level , causing the secondary anaerobic filter element to go partially aerobic and then to return to the anerobic condition has increased the efficiency of the filter system and reduced the biological cycle time . in particular , water percolating down through , or along the surface of , the aerobic filter ( 9 ) will tend to collect remaining protein material . as the water level at the secondary anaerobic filter ( 8 ) decreases this protein material is deposited on , and trapped by said secondary anaerobic filter . this protein material is thereafter decomposed providing the invention with an added capability to function as an equivalent protein skimmer without the requirement of additional equipment or cleaning . fig6 and 8 depict the corresponding installation in a filter system which is separate from the aquarium . while the operation of the filter system is identical to that described for the integral filter system , the separate filter system has a fourth compartment into which aquarium water is received . viewing fig6 and 8 it can be seen that an added wall element ( 24 ) creates a fourth filter chamber . aquarium water is brought to this input chamber through any of the means well known in the art . in the depicted embodiment a siphon tube ( 11 ) draws water from the lower levels of the aquarium to be filtered and fills the filter input chamber until the water level matches the aquarium water level . the input port ( 1 ) is now located toward the bottom of this added wall element ( 24 ). in all other respects the separate filter system functions in a manner identical to the integral system whose operation was described above . the output elbow ( 5 ) is shown emerging from the end of this filter embodiment but it is understood that this is intended to return filtered water to the cooperating aquarium and this elbow will be connected through appropriate means , known in the art , to accomplish this task .
an aquarium filtration system , biological and mechanical in nature , having the capability to include chemical filtration . the system uses high - density biological filter elements in a series of chambers operated by a single pump . both aerobic and anaerobic bacteria colonies are used for water filtering .