XIX. Intermediate Filtration - Specialty and Purpose Specific Add-ons
This article discusses Ultraviolet Sterilizers, Ozone Generators & Calcium Reactors
Mature reef tanks teaming with life from microscopic protozoa and bacteria to the coral and fish will develop needs in time unique to a newly established tank. Once pristine tanks may begin to fall victim to cyclical algae or bacterial blooms, aging may be making fish more susceptible to infection or accumulated trace elements may have been neglected to lead to hampered or slow coral growth. To address the more advanced requirements of mature tanks there are several components available to the more experienced aquarist.
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Ultraviolet Sterilization
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Ultraviolet light has long been used in sanitation applications due to its ability to eradicate bacteria and other pathogens. The wavelengths of ultraviolet light disrupt cell function within many of these organisms killing them, the microscopic remains to be later removed from the tank through a protein skimmer. For aqueous applications, an ultraviolet light bulb is housed within a quartz sleeve, sealed away from the water that is exposed to the bulb as a function of the device. Baffles are often incorporated to slow the water passing through the sterilizer to increase exposure time to the ultraviolet radiation.
The longer the water is exposed to the bulb the more effectively sterilized the water will become. While slow rates are required to control pathogens like protozoa, bacteria, and parasites, simple algae control is obtained with relatively low exposure time. As the U.V. bulb irradiates the cells within the water column a scale will form on the quartz sleeve in time. It is important to keep this surface clean at all times and to continuously remove this scale as it forms. When servicing an Ultraviolet sterilizer assure power is off to the unit. The light is very damaging to our eyes and can have a lasting impact on our vision. As a result, the internal workings of an ultraviolet sterilizer are completely shielded and to know if your unit is functioning you check an indication window.
When the bulb inside the unit burns out, light captured and refracted through the indication window and the small semitranslucent indicator will not glow. Power off the unit and replace the bulb completely reinstalling the unit within the quartz housing and protective outer shield before powering on the unit. If the indicator does not glow, shut off the unit before attempting to adjust any connections and reassemble the unit completely before powering. Under no circumstances should an ultraviolet sterilizer bulb be serviced and changed while there is power to the unit to avoid long-term vision problems.
Ozone Generators
Ozone generators are an alternative to the above with similar purpose. The growth of algae and the threat of pathogens is reduced through the application of ozone. Ozone(03) is a highly unstable bond of three oxygen atoms that quickly oxidizes other compounds, splitting apart and altering the composition of the initial compound. Ozone is usually applied through specialized ozone generators designed for the aquarium trade. This unit is used to feed the venturi of a protein skimmer and allows for the application of pure ozone to aerate the aquarium, oxidizing bacterial slimes, and nutrients and raising the water column capability to continue doing so. It is a highly effective means of disinfecting the water in aquariums often employed by commercial and laboratory applications.
Ozone is highly unstable and able to leach to the air from the water column, this has serious health concerns for all life, additionally elevated ozone within the water column can cause stress and death to inhabitants. Use of a properly reviewed and rated ozone detector is a must. Improper use of ozone can lead to the death of aquarium inhabitants, other pets that come into contact with the air around a tank or serious health effects up to the death of any humans exposed to excess ozone generated by an aquarium. While a great option for the advanced aquarist with adequate resources and knowledge of the process, ozone should be avoided with ultraviolet sterilizers employed in most circumstances.
Calcium Reactors
While pathogen and algae control may be a factor of a maturing tank that we want to control through the additional equipment, some aging tanks require instead of supplementation. As coral grow they convert calcium, magnesium and several other trace elements into skeletal structures. Larger colonies have larger demands for optimum growth, as your coral grow and mature these vital elements may become depleted between water changes leading to stunted coral growth. To supplement the addition of calcium and other trace elements many aquarists use liquid additives or kalk. These process can be time-consuming or become quite costly with larger systems over one hundred gallons or in aquariums with dense populations of stony coral.
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For applications where calcium and the other trace elements are at an extreme premium, the application of a calcium reactor offers an alternative to the addition of supplements. Comprised of three main components calcium reactors mix carbon dioxide with a steady supply of tank water to maintain a lower pH within a reaction chamber. The reaction chamber is filled with aragonite based media that begins to break down when exposed to the lower pH of the reaction chamber. The calcium and trace elements from within the aragonite are concentrated into the water column of the reaction chamber and slowly dripped into the system.
The pH within the reaction chamber is low enough to have detrimental effects on your aquarium. Too much of the high alkaline solution being applied leads to accumulation over time and leads to precipitation of the calcium, a clouding at the water is saturated with calcium and the remaining particles become insoluble to the solution within our aquarium. If we do not allow the water enough time in the reaction chamber, instead of the water we introduce to the tank will be laden with carbon dioxide which will strip the available calcium and magnesium from the water column of our aquarium. Due to the risk of pH altering effects as a result of malfunction, a pH controller should be used whenever calcium reactors are employed.
A pH controller is a device with a probe that detects pH of a solution. This device serves as a relay between a power supply and a given device. When the pH of the solution is within the preprogrammed range the circuit is closed and power can be transferred to the device from the power supply. When the pH of the solution measured fluctuates outside of the preprogrammed range the circuit is opened and the power is no longer relayed from the power source, effectively powering down the device. PH controllers passively monitor the output of a calcium reactor and serve as a failsafe to assure that the calcium reactor is shut off until the pH fluctuation is addressed or the situation balances on its own. When the pH of the tank returns to the desired level the calcium reactor will have power returned to it so it is important in the case of a drastic swing that has caused a shutdown, the root cause is addressed or the system will be shut down again. Routine and frequent powering off and on of the calcium reactor can lead to cavitation of the supply pump or shorten the lifespan of other pump components.
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Once a tank has matured and the organisms within have become well established, the need for sterilization and supplementation through more advanced components becomes greater. The investment of time and love into these works of art is worth preserving with as much preparation for long-term success as possible. Neither of these options are required to start a reef aquarium, however, installation of components but reservation of use until a need arises is a great precaution. This not only assures the availability of components when the need arises but also assures no additional complications when addressing the need as it develops. When the needs develop components can be simply plugged in without unexpected alteration to your schedule or budget.