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How to Clean Hard Water Stains in an Aquarium

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Hard water stains can develop in your aquarium if you use water with a high mineral content to fill your tank. These stains can make it difficult to see your fish through the glass, as well as cause your entire tank to appear discolored. You can remove hard water stains by properly cleaning the glass in your aquarium.

Step 1

Remove all your fish from your tank by scooping them out of the water with your net. Place the fish in your backup aquarium, where they can safely reside while you clean the hard water deposits off your primary aquarium.

Step 2

Scrape off as much of the hard water deposits as you can with your aquarium scraper.

Step 3

Mix half a cup of white vinegar with a gallon of water and pour the mixture into a spray bottle. Spray on the deposits and then scrub them away with a washcloth.

Step 4

Rinse fish tank thoroughly with clean, fresh water. Make sure to completely wash away all possible traces of vinegar completely from the tank. Refill your tank with clean, fish-safe water and return your fish to their newly cleaned tank.