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Recirculating Aquaculture is a technique for raising water borne animals in a closed (usually indoor) system which minimizes water consumption, provides maximum control of the livestock’s environment, and reduces the risk of exposure to parasites, disease, and predators.

To establish a successful RAS, the following primary components are necessary to create a habitat which livestock can thrive:

    • Tanks / Water – Large enough to contain large quantities of livestock. Depending on the species of livestock being raised, stocking densities vary greatly. As a general estimate, ½ pound of livestock per gallon of water is a range to provide a sense of the quantity of livestock in an RAS tank.
    • Pumps –Large quantities of water must be moved into and thru RAS tanks to sustain the environment of the livestock during their food consumption and respiration.
    • Oxygen Injection – For the stocking densities of successful Recirculating Aquaculture Systems, oxygen must be saturated into the water  “Oxygen cones” saturate the water prior to the water being pumped into the tanks, or  stones  bubble gaseous oxygen or air up thru the tanks. Usually the oxygen is brought to the RAS site in a liquid ultra-cold form.
    • Bio-Filtration – Because of the stocking densities of livestock metabolizing food, an ecosystem must be established for the breaking down of ammonia into Hydrogen and a less toxic Nitrite by naturally occurring bacteria. The nitrites will ultimately be broken down into an even less toxic nitrate by yet another naturally occurring bacteria that will thrive in the bio-system.
    • Solid Waste Removal – Solid Wastes are removed by screen filters, swirl separators or sedimentation.
    • Disinfection – To reduce the likelihood of disease, the pumped water of an RAS can be passed thru a UV Light Filter to disinfect the water before returning to the fish tanks. Ozone injection is also a strategy that can be used with, or in place of UV Light for disinfection.
    • Lighting – Depending on the specie being raised in an RAS, light can be critical to animal health and maximum growth rate. If natural light is not employed, wavelength and duration of artificial light must be considered. The spectrum distribution of various artificial light sources can be compared in the June-July 2013 Issue 155 of “Home Power” magazine.{
    • Temperature Control – To maximize livestock growth, the water temperature must be maintained at the level desired by the species being grown. Heating can be done by natural gas or propane, or the direct conversion of electric energy to heat by resistance coils. However, the most efficient means to heat the waters of a Recirculating Aquaculture System is not by creating heat but rather by the movement of free heat from either an air source or water source, using a heat pump.

A heat pump also allows the removal of heat from the RAS when temperatures exceed ideal levels for livestock growth, which is not possible with traditional gas fired combustion systems. Air source heat pumps can provide the needed heat and chilling year round dependent upon outdoor temperatures. When average air temperatures drops below 50°F, the traditional air source heat pump has a reduced capacity and efficiency. When average air temperatures are routinely below the 50°F, a gas heat back up to the air source unit is recommended. The most efficient heat pump system is the geothermal/water source heat pumps which harvest heat from the solar energy stored in the ground or bodies of water. Heat pumps routinely deliver heating and cooling/chilling at 1/4th the cost of burning fossil fuels or electric resistance heating.

  • In general, heat pumps are very energy efficient. A heat pump is able to move far more energy than it uses. A heat pump uses a refrigeration cycle exactly like your refrigerator or air conditioner uses. Heat pumps are a proven safe, economical and trouble-free system with very low operating costs, long lifespan, and small environmental footprint.
  • There are two types of heat pumps: (1) air source and (2) water source/geothermal.
  • Applied to an RAS system, a heat pump simply moves heat from the air (or water) and transfers it to the culture water.

For RAS, either air source heat pumps or water source/geothermal heat pumps can be used. Both are energy-saving units. In RAS, water temperature control is essential. Your geographical location of the RAS is a major factor in determining if an air source or a geothermal water source heat pump is the best choice.

  • While an air source heat pump is an excellent choice, the air source unit is dependent upon the outside air temperature remaining 50°F or above to maintain the desired temperature for the RAS. Air source units have to have an outdoor air source; therefore, the units are usually installed outdoors – exposing the unit to ambient environmental conditions (rain, snow, airborne contaminants). Air source heat pumps can also be used to chill the water. Typical life span of an air source heat pump is 10-12 years.
  • Geothermal/water source units are not dependent on outside air temperatures, but on the geothermal water source. A geothermal/water source heat pump is more efficient than the air source with a consistently higher C.O.P. (Coefficient of Performance) due to a more constant energy source temperature. Geothermal heat pumps can also be used to chill the water. Also, water itself has inherent improved heat transfer characteristics than air. Geothermal units are not dependent on air flow and can be located entirely indoors. Typical life span of a geothermal water source heat pump is 12-20 years.

AquaCal® Heat Pumps (air source or geothermal/water source) are ideally suited for Aquaculture, Aquarium and AquaPonics Applications.

  • AquaCal® is the largest heat pump manufacturer for pools and spas in the world and the units are made in St. Petersburg, Florida USA. We are excited to join our heat pump expertise with the professionals of the Aquaculture, Aquarium and AquaPonics industries.
  • AquaCal® Heat Pump water flow rates ideally match the requirements of Recirculating Aquaculture Systems (RAS). After all, culture tanks are little more than “Swimming Pools for Fish”!
  • The Titanium ThermoLink® heat exchangers are rugged and perfectly suited for fresh water as well as full strength salt water (up to 35,000 ppm of salt) in the culture and as the source water in a Water Source (Geothermal) Unit.
  • AquaCal® Heat Pumps offer ease of operation, tight temperature controls (± 1°F), and high unit efficiency.
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