Removing White Residue on Aquarium Glass

Using a razor blade or scraper

This method is not very effective but might work for you if the build-up on the aquarium glass isn't too hard. All you would need for this is a razor blade or probably a scrapper.

• Get a razor blade or scraper
• Gently use any of the tools to remove the white residue from the areas affected.
• You can also add a bit of water to the surface and continue scrapping.

Using sponge and Rock Salt

The sponge and Rock salt method won't do any good if you leave the white residue unattended for a very long time. If the white residue on the glass is fresh, this method would definitely help get rid of it.

• Get a foam sponge and insert it inside the water for a few seconds.
• Bring out the sponge and add a fair amount of rock salt to the sponge.

Using Vinegar

This method really works, you would need to use vinegar along with a damp cloth, sponge, or just about anything that'll help get rid of the white residue. The vinegar helps to soften the buildup on the aquarium glass.

Sandpaper

• Cut the sandpaper grit into small sizes that you can use.
• Use the sandpaper to scrub the areas where you have white residue and you should see significant improvement.
• After scrubbing for a while, use new sandpaper and continue the scrubbing.

Prevent White Residue on Aquarium Glass

• Ensure that you have good water flow in your aquarium system.
• Use hydrogen peroxide to spritz on the surface.
• Use distilled aquarium water instead of tap water.
• Put a plastic wrap over the aquarium glass and replace it every time you feed the fish or once every week.

How do you remove hard water stains from Aquarium glass?

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.

• Remove all your fish from your tank by scooping them out of the water with your net. After that, safely reside while you clean hard water deposits off your primary aquarium. 
• Scrape off as many of the hard water deposits as you can with your aquarium scraper. 
• Mix half a cup of white vinegar with a gallon of water and pour the mixture into a spray bottle. Spray on deposits and then scrub them away with a washcloth.
• 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.

What Causes a White Film on Aquarium glass?

As mineral-rich aquarium water (hard water evaporates, the gaseous water leaves behind the heavier elements that adhere to each other and to the glass, leaving an ugly, streaky white residue behind.

The white build-up is caused by calcium deposits or minerals found in water. You can use vinegar to remove the buildup. If you don't have vinegar, you could also use lemon juice, although vinegar works best. Just put some on a clean cloth and rub over the calcium deposits.