Many reef and saltwater aquarium hobbyists prefer the look of coralline algae covering the live rock in their aquariums. Coralline algae turn the natural dull appearance of live rock into pleasant pink, purple or other pleasing colors. This algae not only covers the live rock, it will also grow on the inside walls of the aquarium and equipment. Unlike most algae, it has calcareous deposits contained within its cell walls, making it difficult to scrub from glass and equipment.
When coralline algae grows on glass aquariums, it can be removed with a little muscle, patience and an algae scraper with a stainless steel blade. The trick is to clean the glass often to keep coralline algae from building up making it very difficult to remove. Use caution when scraping around seams of an aquarium so you do not peel off the silicone glue. For glass aquariums Kent Marine makes a quality scraper which includes a stainless steel blade available in several sizes including the Pro Scraper Short and Pro Scraper 12"
Acrylic aquariums scratch easily; they require a special scraper to clean coralline algae. A good choice for cleaning acrylic is Kent Marine's Short Pro-Scraper with plastic blade.
As mentioned, coralline algae can grow on submerged aquarium equipment including powerhead covers. These covers have slots cut in the plastic housing to allow water to flow in and out and to keep livestock from getting in. As coralline algae grow over the powerhead cover, it begins to slowly cover these slots making them less efficient.
The easiest way to clean coralline algae off powerheads is to put them in a solution of Crystal Clear Aquatics Zap-Cal Descaler. The amount of coraline build up will determine how long it will need to soak. Usually after thirty minutes the coralline will turn white and you can remove it from the bath. Use a nylon brush (included with Zap Cal) to scrub off the remaining white coating. The bath also removes other common types of algae very quickly.
The manufacturer of Zap-Cal claims it is safe for use with plastic, ceramic, rubber, PVC, titanium, copper, nickel and, for short term use, with stainless steel. For more information on Zap-Cal Descaler Click Here.