How to Start a Saltwater Aquarium Using Natural Filtration

Once a saltwater aquarium is set up, maintenance is very easy, but getting it to that point presents a challenge, especially if you are going to use a natural filtration system. While most saltwater aquariums rely on wet-dry mechanical filtration systems, it is possible to use an all-natural system as long as you include water pumps to keep the water circulating. This set-up takes patience and an acute attention to the chemical profile of your tank as well as knowledge of saltwater ecosystems and how to tweak them.

Things You'll Need

  • Sea salt
  • Coral
  • T5 high-output fluorescent or metal halide lighting
  • 75 lbs. of live rock (or an equivalent amount so the tank capacity in gallons and the lbs. of rock are in a 1:1 ratio)
  • Live sand
  • Saltwater aquarium chemical test kit
  • 75-gallon or larger fish tank with built in overflow
  • Sump system
  • Hydrometer
  • Water heater
  • Power-head
  • Damsel fish
  • Saltwater plants
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Instructions

    • 1

      Set up the tank in the location where it will reside. The tank will be extremely heavy after it is filled and impossible to move without emptying it and restarting the entire system.

    • 2

      Place 3 to 4 inches of live sand in the bottom of the tank. Live sand contains nitrifying bacteria (nitrosoma) that convert fish waste (ammonia) into nitrite. There is also another bacteria (nitrobacter) that converts the nitrite to nitrate but it is present in only small amounts in the live sand.

    • 3

      Fill the tank with distilled water, leaving at least 6 inches at the top to accommodate the live rock and coral you will be adding. Add sea salt at the ratio of 1 tablespoon per gallon and check the specific gravity with a hydrometer. The specific gravity should be in the 1.020 to 1.023 range. Add salt until you reach this specific gravity. If you put in too much salt and the specific gravity gets too high, remove some of the water and add more distilled water to lower the specific gravity.

    • 4

      Install the sump system and hook up your power head. Getting the water flowing in the tank will help the bacteria start feeding on any residual ammonia in the sand.

    • 5

      Install the water heater. Bring the temperature of the tank up to 75 to 80 degrees Fahrenheit.

    • 6

      Install the live rock and coral. Make several caverns for your future fish to hide in.

    • 7

      Set up the halide or high-output fluorescent lighting system and turn it on. Live rock can subsist in a low-light environment but coral must have high light to propagate the growth of symbiotic algae in them. The algae provides food for the coral.

    • 8

      Let the tank run for 72 hours to begin building up the biological filtration system.

    • 9

      Add damsel fish to your tank to promote bacterial growth. The rule of thumb is to add one damsel per 20 gallons during tank setup. Do not add any other fish to the tank until the nitrogen cycle has completed and the tank has a stabilized environment.

    • 10

      Test the ammonia, nitrite and nitrate levels in the tank with your chemical test kit every few days. The ammonia levels will spike between day 6 and day 8 and then sharply decrease. This will be followed by an increase of nitrite between day 12 and 28. This increase will occur much more rapidly during days 24 to 28 followed by a sharp decrease just like you saw in the ammonia.

    • 11

      Add more fish around day 40. Do not add too many at once because the bacteria will take a while to catch up to the new waste load.

    • 12

      Add saltwater plants to the aquarium around day 60. These plants help remove nitrate from the water. If your nitrate levels begin to get higher than 20 parts per million consider doing partial water changes monthly.