How to Build a Calcium Reactor for a Salt Tank

A calcium reactor is a container in which calcium carbonate (CaCO3) is exposed to carbon dioxide (CO2) and through which aquarium water is pumped. The continued injection of carbon dioxide lowers the pH of the water within the reactor, thereby causing the calcium carbonate to dissolve. Water rich in calcium and with an elevated alkalinity is then pumped into the aquarium where hard corals use the calcium to build their skeletons. Calcium reactors therefore replace the need for regular additions of calcium to a marine aquarium. Although a number of commercial calcium reactors are available, it is possible to build your own.

Things You'll Need

  • Nylon straps
  • Carbon dioxide in a pressurized container
  • Regulator, including valves and gauges
  • Solenoid
  • Needle valve
  • Calcium reactor
  • Aragonite media
  • Small plastic jug
  • Small amount of aquarium water
  • Recirculation pump, with associated tube
  • Feed pump, with associated tube
  • Alkalinity feed tube
  • Sump
  • Alkalinity test kit
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Instructions

    • 1

      Use straps to secure the pressurized carbon dioxide bottle in a safety cage or to the aquarium stand or cabinet. Be aware that if the collar of this pressurized bottle is damaged through a fall, the bottle will be propelled forward with considerable force and speed.

    • 2

      Position the pressurized carbon dioxide bottle away from any type of heat source, as high temperatures cause these bottles to explode.

    • 3

      Attach the regulator, which consists of valves and gauges that are used to control and monitor the amount of carbon dioxide that is released, to the pressurized bottle.

    • 4

      Attach the solenoid to the regulator. Should you experience a power outage, the solenoid will switch off the flow of carbon dioxide and thereby prevent it from escaping into the aquarium

    • 5

      Attach the needle valve, which is used to make fine adjustments to the carbon dioxide flow rate, to the solenoid.

    • 6

      Remove the lid of the calcium reactor and fill the reaction chamber with aragonite.

    • 7

      Pour aquarium water into the calcium reaction chamber, carefully. Be aware that you will not require much water, as the chamber already contains the aragonite.

    • 8

      Replace the lid and ensure it is secured tightly.

    • 9

      Place the calcium reactor below or behind the aquarium.

    • 10

      Attach the carbon dioxide tube originating from the needle valve, to its port on the lid of the calcium reactor

    • 11

      Attach the alkalinity feed tube to its port on the calcium reactor and place the free end into the aquarium or aquarium sump, which is a reservoir that stands below the aquarium and is attached to it, via tubing and pipes.

    • 12

      Attach the recirculation pump via tubing to its port on the lid of the calcium reactor.

    • 13

      Attach the feed pump, via tubing to its port on the lid of the calcium reactor.

    • 14

      Plug the recirculation pump into a wall power supply and turn on.

    • 15

      Plug the feed pump into a wall power source and turn it on.

    • 16

      Turn on the carbon dioxide. Allow the system to run over night.

    • 17

      Adjust the drip or effluent rate to approximately 100 cc per minute.

    • 18

      Use a new and high-quality test kit to measure alkalinity in the display aquarium. An alkalinity reading of 12 DKH is optimal.

    • 19

      Adjust the carbon dioxide flow rate as required. A higher amount of carbon dioxide will cause a higher alkalinity reading.