DIY Metal Halide Saltwater Aquarium

Keeping an aquarium full of fish and other wildlife is a simple and relatively easy way to bring animals into your life. Maintaining a saltwater tank opens up a realm of new possibilities. Saltwater fish are more colorful than freshwater fish, and there is a greater variety of marine life that can live in saltwater. But saltwater tanks also come with greater challenges, like maintaining the water alkalinity and salinity balances, finding saltwater fish that can coexist and decorating and maintaining the tank. Using metal halide lighting adds another complication to this mix.

  1. Setting Up a Saltwater Tank

    • Before you do anything with lighting, you need to set up your saltwater tank. Decide on the size of your tank and where you're going to keep it. Put the aquarium in a place that maintains a fairly consistent temperature, where it won't experience much direct sunlight. Place your aquarium in a place that is convenient--you won't want to move it once it's filled with water.

      Prepare the equipment that's going to go inside your saltwater tank, including filtration system and thermometer. Install this equipment in the tank before you put the water in, but do not turn it on. Turning it on without any water present will burn it out.

      Prepare your water using salt mix (available at fish or pet stores). Place the submersible pump and heater in the bottom of a 20-gallon trash can, which is where you're going to prepare your first batch of saltwater. Always prepare plenty of salt water; you'll return to your supply when performing water changes. Use an RO/DI to prepare enough water to fill the trash can (never use tap water, as it contains chemicals that will kill your fish and coral). Add a salt mixture (available at pet stores) per the manufacturer's directions.

      Allow the saltwater to age for 48 hours in the trash can. During this time, add your plants, coral, substrate and live rock to your aquarium. Keep in mind that live rocks and coral need water to survive; don't leave them sitting in the aquarium for days without water. When your saltwater is ready, add it to your aquarium. Turn on the filtration system and allow it to run for a day as a test. Check for leaks, adjust the temperature and balance the nitrates and alkalinity at this time. Most saltwater wildlife needs a pH between 8.2 and 8.4. Never let it drop below 8.0. The nitrate reading should be between 5 and 20 parts per million. Take a sample of your water to your local fish store for help in testing it.

    Metal Halide Lighting

    • Metal halide lights are the best lights for maintaining some delicate corals because they provide bright, hot, intense lighting. They also up the intensity of your marine life: fishes and plants will grow more quickly, and have brighter colors with metal halide lighting. They can, however, cause problems, so require specific setups and precautions.

      Set up fans or chillers to keep your water at a consistent temperature in the face of the heat generated by the metal halide lights. Fans should blow directly across the surface of the water. Install a chiller per the manufacturer's instructions. Since all three of these devices will increase evaporation of the water, make sure you check your water level consistently.

      Mount special hoods for your metal halide lights (available at pet and aquarium specialty stores). MH lights must be held at least 12 inches away from the water, due to their heat, if your aquarium animals are going to be safe. MH light hoods do not eliminate the need for fans or a chiller in your aquarium.