How to Keep a Saltwater Aquarium Crystal Clear

Written by naomi bolton Google
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How to Keep a Saltwater Aquarium Crystal Clear
You will be able to view fish better in clear aquarium water. (yellow fish in aquarium image by Sujit Mahapatra from

Marine fish and invertebrates, such as corals, come from crystal clear reef environments. For this reason, and in order to create an attractive display, saltwater aquarium enthusiasts attempt to keep the water in their tanks absolutely clear. A number of filters, including a protein skimmer, will remove debris and detritus from the water and keep it clear. By not overstocking and overfeeding the fish and invertebrate animals, you can go a long way to ensure clear water conditions. Regular water changes and the use of reverse osmosis to replace evaporated water will also help.

Skill level:

Things you need

  • Protein skimmer
  • Fine filter pads
  • UV sterilizer
  • Activated carbon
  • Submersible pump or powerhead
  • Synthetic sea salt
  • Heater
  • Thermometer
  • Hydrometer
  • Reverse osmosis unit

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  1. 1

    Install a protein skimmer or foam fractionator that is rated for the volume of water in your aquarium. Molecules of debris and detritus will attach themselves to the fine bubbles produced by the skimmer and will be removed from the water column.

  2. 2

    Install fine filter pads in canister filters. These pads function as mechanical filters and physically trap dirt, which would otherwise be circulating through the aquarium water.

  3. 3

    Install a UV sterilizer, which will destroy bacteria and unicellular algae. This material will subsequently be filtered out of the water by the canister filter or protein skimmer.

  4. 4

    Add activated carbon to your canister filter. The myriad pores and passages in each piece of carbon will trap molecules of metabolic waste and other debris and remove them from the water.

  5. 5

    Aim the exhaust nozzle of the pump or powerhead into the water column and not at the substrate. If you are using very fine aragonite or beach sand, the force of the water from a pump will disturb the substrate sufficiently to keep some of the sand in suspension.

  6. 6

    Feed your fish only as much as they will consume in a few minutes. Decaying leftover food will cause bacteria blooms that will give the aquarium water a cloudy appearance.

  7. 7

    Stock only the number of fish and invertebrates that the volume of water in your aquarium can accommodate. Overstocking will cause the quality of the water to drop.

  8. 8

    Change 10 per cent of your water on a weekly basis. Ensure that the new water is the same temperature and specific gravity as the original water. Use a hydrometer to check specific gravity.

Tips and warnings

  • Use reverse osmosis water in the place of tap water to replace aquarium water that has evaporated. Tap water often contains impurities that contribute towards cloudy water conditions, while water that has passed through a reverse osmosis unit has been filtered.

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