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How to Lower Specific Gravity in an Aquarium

Specific gravity of an aquarium refers to the amount of dissolved salts in your aquarium water. Most marine species require a specific gravity of 1.023 to 1.025 for a standard reef aquarium. It's important to have the proper range of specific gravity, which maintains the aquatic environment for your fish and invertebrates. Sometimes, evaporation or a salt spill can accidentally raise the level of specific gravity in your tank. In situations like this, quickly returning the specific gravity to the preferred range is critical to the survival of your marine life.

Things You'll Need

Hydrometer
Water
Bucket

Instructions

- 1
  Plunge a hydrometer into your tank until the reservoir fills with water. A hydrometer contains a needle or arm which, when immersed in water, points to a chart showing the level of specific gravity. Hydrometers are commonly available at local pet stores or aquarium specialty shops.
- 2
  Remove the hydrometer and read the specific gravity where the arm points to on the scale.
- 3
  Slowly add fresh water to the tank one quart at a time using a bucket, making sure to check the specific gravity with the hydrometer after every quart. Use a slow, even pour to give the water time to combine with your tank's established water. Pouring too quickly can disperse salinity in your tank and harm fish and invertebrates.
- 4
  Continue adding fresh water to the tank until the specific gravity drops to the proper level.

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