How to Get Calcium off an Aquarium

Transfer your fish to a second tank or other suitable container, if the calcium buildup is on the inside. Once the fish are removed, drain the tank. If the calcium is on the outside, you won’t need to drain the tank. The actual cleaning procedure is the same either way.

Dilute one-half cup of white vinegar in one-half gallon of water. Fill a spray bottle with this solution.

Spray the calcium buildup with vinegar, and allow it to soak in for a couple of minutes. Use a paper towel or rag to scrub the area, until the calcium is removed. You can also use a paper towel soaked in undiluted vinegar, rubbing it directly on heavy deposits. For stubborn spots, try using a mild scrubber pad -- designed for scrubbing glass and plastic without leaving scratches. Use a plastic scraper for any spots that still don’t come off.

Wipe the area you have cleaned with a paper towel or rag dampened with clean water. This removes any residue and remaining vinegar. Allow the tank to dry completely.

Refill the aquarium with water. Test the pH of the water, and make any adjustments needed. Once everything is ready, return your fish to the aquarium.