Please visit our Sponsors

Related FAQs: Calcium Reactors 1, Calcium Reactors 2Calcium Reactors 3 Calcium Reactors 4, Calcium Reactors 5, &
FAQs on Calcium Reactors:
Rationale/Use, Selection, Installation, Operation, Media, Measuring, Trouble-Shooting, By Makes/Models, & Calcium and Alkalinity, & FAQs on: The Science of Calcium & Alkalinity, Importance, Measure, Sources, Use of AdditivesTroubleshooting/Fixing, Products, Kalkwasser 1

Related Articles: Marine Maintenance, Marine Water Quality Articles, Kalkwasser, Understanding Calcium & Alkalinity, Calcium in Marine Aquarium Maintenance





By James Gasta


One of the main ingredients for successfully growing SPS/LPS corals is lighting, and lighting of the correct spectrum of which corals best respond to and rapidly grow.

Another important key ingredient is calcium and magnesium. Aquarists with larger tanks generally prefer to use a calcium reactor which makes it much easier to maintain the calcium level (400-440ppm) in a reef aquarium. Magnesium isn’t absorbs quite as fast is calcium is in a well stocked coral reef tank and this supplement is usually added on a weekly basis to maintain recommended level of 1280-1300ppm. A general guide line is to maintain magnesium levels on a 3 to 1 ratio with the calcium level. That is if the calcium level is 425ppm, the magnesium level should be close to 1275. Without this proper balance, corals cannot absorb the available calcium present in the system. To further clarify this so it is easier to understand, consider that if your calcium level is 420ppm, but your magnesium level is only 1100ppm, only 366ppm will be available to the corals. If your magnesium level is 1200ppm, then 400ppm of the 420ppm available calcium will be available to the corals.

Calcium reactors are a good investment, particularly in larger systems for maintaining proper and stable calcium levels.

How do calcium reactors work and what components do I need?

Graphic courtesy of www.marinedepot.com

  1. Calcium Reactor - This is a pressurized container filled with calcium based media. CO2 and aquarium water are mixed together inside the reactor. The acidity generated by the CO2 slowly dissolves the calcium based media which supplies calcium to your water as well as buffers to maintain alkalinity. The amount of CO2 injected is what regulates the calcium level in a system.
  2. Input Water – Supplies the reactor with water.
  3. Dosing Pump – Used to force water into the reactor. There are several ways to accomplish this such as power heads or gravity feed. A power head is recommended over gravity feed.
  4. CO2 Cylinder – Stores CO2 gas for injection into the reactor.
  5. CO2 Regulator – Reduces the output pressure from the CO2 cylinder into the reactor. A solenoid is also used to regulate the CO2 to the reactor and is controlled by a digital pH controller.
  6. CO2 Gas Line – Used to feed CO2 gas from the CO2 cylinder to the calcium reactor.
  7. pH Controller – Used, and needed to control the CO2 output which is based on the pH of the effluent water or the water present in the sump.
  8. Water Return Line – Carries the calcium rich water from the reactor back to your sump or aquarium.
  9. Drip Cup – This is a container installed on your sump or aquarium that collects effluent water returning from the reactor. This is where your pH probe should be placed to monitor the pH inside the reactor which in turn controls the solenoid feeding CO2 into the reactor by means of a digital pH controller.

Photo credit – Marine Depot


Hopefully I have explained in a concise way how a calcium reactors works and the components that are needed to properly use this device. By maintaining proper calcium and magnesium your SPS/LPS corals will take on much better coloration and increase the rate of growth.

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: