How to Kill Macro Algae in Reef Aquariums

Nuisance algae is the bane of reef aquarium hobbyists. Algae grows in the presence of light and nutrients. Reef aquariums require intense lights, including powerful metal halide lamps, to allow corals, anemones and other invertebrate creatures to photosensitize. Marine fish and invertebrate animals also produce metabolic waste on an ongoing basis, which fuels the growth of unwanted algae. Reef aquarists can, fortunately, rid their aquariums of nuisance algae by following a few simple husbandry regimes.

Things You'll Need

  • Reef aquarium, complete with filters
  • Synthetic sea salt
  • Reverse osmosis water
  • Natural sea water (optional)
  • Protein skimmer
  • Sump
  • Mechanical filter material
  • Gravel vacuum
  • High-quality activated carbon
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Instructions

    • 1

      Change 10 percent of the aquarium water each weak. Water changes dilute the concentration of nitrates and phosphate, which fuel nuisance algae. Use a good quality synthetic sea salt and reverse osmosis water, as tap water can contain both nitrates and phosphates.

    • 2

      Place a powerful protein skimmer into the aquarium sump. Protein skimmers export nutrients from the water by producing masses of ultra-fine bubbles to which the protein molecules attach. By removing the metabolic waste of fish and invertebrate animals, you lower the concentration of nitrate, or NO3-, which is a principal nutrient source for nuisance algae.

    • 3

      Clean the mechanical filter material in your canister, hang-on or internal filters. Dirty mechanical filter material is a prime source of nitrates and phosphates.

    • 4

      Vacuum the substrate if the aquarium is overstocked and overfed. Marine substrates in these tanks become reservoirs for nutrients, which unwanted algae feeds on.

    • 5

      Purchase only activated carbon, with is low in phosphates. Activated carbon is a useful filter material, but poo-quality products have high phosphate content. This low-grade carbon can cause more harm than good in a reef aquarium that is already experiencing an algae problem.

    • 6

      Perform regular fresh water top-ups with reverse osmosis water. Water evaporates from the reef aquarium on an ongoing basis, but only the fresh water component. The minerals remain behind and the salinity subsequently rises.

    • 7

      Replace old lights. The spectrum of fluorescent tubes begins to shift with age and can encourage growths of unwanted algae if their useful life is almost exhausted.

    • 8

      Remove fish and invertebrate animals if the aquarium is overstocked. The more livestock the reef aquarium contains, the more metabolic waste will be released into the water. Both the additional metabolic waste and presence of uneaten food will fuel nuisance algae growth.