What Do You Use to Lower Calcium in an Aquarium?

An aquarium requires the perfect balance of chemicals if you're going to keep its inhabitants healthy and happy. Calcium is a mineral that often makes its way into home aquariums via tap water. While it does not normally lead to any major aquarium problems, there is still a small amount of danger associated with abnormally high levels that may persuade aquarium keepers to lower it.

  1. Calcium Basics

    • Calcium is not generally considered a bad thing in the home aquarium. While freshwater species do not make much use of it, it does not immediately harm them. It will, however, leave ugly calcium residue on the sides of tanks that many find unattractive. It plays a bigger role in saltwater aquariums, as it is used by corals and clams to build their hard shells. However, too much calcium (over 500ppm) could potentially drop the pH of water, which is detrimental to saltwater fish that have high pH requirements.

    Lowering Calcium Biologically

    • The easiest way to permanently lower calcium levels in a saltwater aquarium is to add some corals or clams. These organisms utilize calcium so much that their outer shells are almost exclusively made of calcium carbonate. The more coral or clams that are added to a tank, then the more calcium that will be used up. In fact, lowering calcium in a reef tank is not so much a problem as keeping it up, which many keepers do with various calcium supplements designed for aquariums.

    Lowering Calcium Mechanically

    • One of the most obvious solutions to calcium that is too high is to do a simple water change. This is easy for freshwater fish and will help dilute the calcium-rich water already in the tank. However, this is a more dangerous proposition for saltwater aquariums, which are very sensitive to changes. Never change more than a fourth of the water at a time in a freshwater tank or a fifth of the water in a saltwater tank.

    Lowering Calcium Chemically

    • Water softeners are used primarily in freshwater tanks that are filled with hard tap water. Hard water is described as water that contains ions of magnesium and calcium. The water softener, which comes as a pillow, liquid or powder, replaces the calcium ions with sodium ions, "softening" the water.

    General Prevention

    • The best way to keep the calcium levels in your aquarium low is to just avoid it altogether by not filling your tank with tap water or mineral water. Calcium, along with other chemicals like chlorine, are often found in tap water while mineral water contains calcium, magnesium and various other minerals. Use pure water when you fill up your tank, which you'll find in jugs at virtually every grocery store.