How to Raise the Alkalinity in a Saltwater Aquarium

Ensure that the reagents in your alkalinity test kit have not expired. A low alkalinity reading may simply be the result of old reagents in the test kit.

Install a protein skimmer, which is rated for the volume of water in your sea water tank. A protein skimmer that is operating correctly will drive off excess carbon dioxide from the water and thereby assist to raise the alkalinity.

Add buffer powders to your aquarium as soon as the test kit indicates that alkalinity is dropping. Buffer powders contain bicarbonate and carbonate ions that counter the hydrogen ions responsible for forcing the alkalinity down.

Add live coral species to the marine aquarium. Corals use carbon dioxide through the process of photosynthesis, and by removing excess carbon dioxide from the water, assist to raise alkalinity levels.

Include and encourage the growth of large colonies of higher algae, which assist to raise alkalinity levels as corals do, by removing carbon dioxide from the water.

Replace evaporated tank water with a calcium hydroxide solution, instead of tap water. Carbonates and bicarbonates are produced when the calcium hydroxide combines with carbon dioxide in the aquarium water and thereby raises the alkalinity naturally.

Do not overstock your aquarium, as aquatic animals produce carbon dioxide through respiration.

Use a fan to create better air circulation in the room that contains your aquarium. Carbon dioxide in the air, which is high in most homes, is absorbed into the aquarium through the water surface and depresses the alkalinity.

Keep windows open, to improve the air circulation in small rooms. The respiration from people and pets, together with cigarette smoke, contribute to high carbon dioxide levels that cause alkalinity in the aquarium to drop.

Place your aquarium in another room where there is sufficient air circulation to remove excessive carbon dioxide.