XX. Closed Recirculating Systems - Multiple Tank Loops

This article discusses a single example of a Closed Recirculation System

 

     Emulating nature knows only the extent of our imagination. Aquarists may have multiple different tanks with different themes spread throughout their home, or perhaps in a dedicated fish room. When the maintenance of several systems begins to take its toll it is not uncommon for more serious aquarists to loop tanks into existing systems, taking this one step further we can emulate natural filtration processes seen in nature. Tanks arranged and design to facilitate different roles are plumbed together to form elaborate systems that share a single sump and primary filtration system.

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     By combining all the advances in the reef keeping trade with the sciences of biology and chemistry it is possible to design and construct a system that requires very little maintenance compared to maintaining several systems, it is possible to even reduce the need for water changes with this methodology. To achieve this we must focus on the import and export of all nutrients in the aquarium, accumulations of nutrients and depletion of essential and trace elements must be regulated.  By harnessing natural processes and properly maintaining supplementary filtration we create a closed system that is equivalent to that of display venue aquariums and research facilities.

   

The accumulation of nutrients is a critical concern, with multiple tanks and potentially hundreds of inhabitants in each tank the waste will need to be neutralized and exported. To do this we employ several controls. Starting in the sump components rated for the total gallonage of your system including the sump and the volume of plumbing interiors are selected to filter the system:

• Wet/Dry Tower

• Media Reactors

• Oversized Protein Skimmer

• Calcium Reactor

• pH Controller

• Accessory Monitoring Equipment

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    The water from the sump is then filtered mechanically to reduce microbubbles before being pumped to the display(s). One or more tanks may be considered a display, the tank primarily serves an aesthetic purpose in the system and a significant source of waste accumulation and mineral depletion. Live food is dripped into the system, coral and fish consume the live food and create waste while consuming elements in the water column.

 

    The nutrient-rich, low mineral water is drained by an overflow system in the display(s) to a settling refugium. Here a deep sand bed, low current, copious live rock and forests of macroalgae filter particulate matter and nutrients from the water current. Additionally, eggs and offspring of display inhabitant have a chance of settling in this haven. Mangroves are not uncommon in these large refugia these not only extract a large number of nutrients from the water column but provide stunning possibilities for unique aquascapes. While often beautiful in their own right this tank serves to provide nutrient reduction, passive particulate filtration, a haven for detritus scavenging crustaceans and settling coral so it isn't necessarily a display tank and care and reservation should be taken to preserve a low density of fish and coral if any.

 

    Once the flow of the system water has slowed and been partially cleaned of particulates and nutrients the water from our refugium can drain into the next stage of our recirculating system. A collection of fast-growing anemones or coral such as Xenia can be propagated within a confined area of our system to harness their beneficial qualities without risk of an overwhelming invasion in our display tanks. Xenia absorbs excess nutrients from the water column while anemones are voracious particulate feeders. Water leaving this thank has slowed dramatically compared to within the primary display, this allows more time in contact with beneficial bacteria films for phosphate reduction. In addition, the lower flow at this point in the system lends itself to effective ultraviolet sterilization as the next step.

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    The sterilized water can be drained into a Wet/Dry tower to allow for further biological filtration to occur before returning to the sump for nutrient stripping and element supplementation from the components outlined previously. A protein skimmer with its return passed through a filter sock feeds a chamber where a quality heater with thermostat maintains a minimum temp. Into this area we can plumb our calcium reactor, returning elements to the water on its way back to the display.

 

To recap the system process;

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1.) The tank water has entered our system and pumped into a display where nutrients accumulate and particulate, as well as dissolved organic compounds, are formed as a result of live food introduced to the tank. Key elements such as calcium and magnesium are absorbed through coral growth and many other trace elements are consumed through various biological functions.

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2.) The now nutrient-rich element poor water is passed through two stages of natural filtration that allows for thorough nitrification of waste, absorption of nutrients and polishing of water through removing particulate matter.

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3.) The polished, low element and now low nutrient water is then sterilized aiding in water clarity, pathogen reduction and isolation of Xenia and anemones to the tank they reside in preventing their spread to other tanks.

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4.) Low nutrient, sterilized & polished water is then processed further by bacteria based media reactors and remaining dissolved organic compounds are stripped from the water using a protein skimmer, its return filtered with a filter sock to reduce.

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5.) Processed water is heated and key elements are replaced in the final stage of the sump before being returned to the display to begin the process again.

 

    In theory, this system requires reduced water changes as nutrients are sufficiently exported through natural means. Supplemental equipment bridge the gaps where time or space is not available for natural biological processes to occur. The time and investment to create such a system is certainly not for the newly introduced hobbyist and left to the more experienced. Thorough knowledge of components, plumbing, and proper protocols for feeding, quarantine, disease treatment are all prerequisites learned in-time exploring the hobby. This article is meant to inspire hobbyist to continuously push forward with their passion. There are many challenges involved to reef keeping but with a commitment to the purpose, it is possible to face these challenges and arise victoriously.