How to Clean Aquarium Glass White Residue in 5 Steps

how to clean aquarium glass white residue

The white residue on your aquarium glass is usually either limescale or salt creep. While they both may not be harmful to the creature inside, the chalky haze still obstructs the magnificent view of your aquaponics system.

To restore your fish tank to its former glory, you must know how to clean aquarium glass white residue. Learning the correct methods will not only allow you to enjoy the fish’s vibrant colors again but also ensure that you don’t accidentally harm your aquatic pets in the process.

So, how do you get rid of film on top of water in fish tank? Keep reading.

Guide to Clean Aquarium Glass White Residue


What to Prepare

You need the following items to remove hard water stains from glass fish tank. Additional materials are necessary, depending on the method of white residue removal.

  • Fish net
  • A clean and empty tank (or container/plastic cup)
  • Siphon
  • Scraper or razor
  • Spray bottle
  • Vinegar or any weak acid
  • Rock salt and a sponge
  • 1000-grit sandpaper or pumice stone

Step 1: Transfer the fish to another tank or container.


Get a siphon and transfer about 50% aquarium water to a clean, empty fish tank or container. Alternatively, you can use a large plastic cup.

Reserve this water because you will also return it to the fish tank after cleaning.

Grab your fish net and gently scoop fish from the tank one by one. Transfer each fish to the container with the original water. Be gentle in handling your fish to avoid stressing them.

For other aquatic creatures, such as shrimps, put them into a separate container with water from the tank as well.

Step 2: Remove accessories, decorations, and other livestock.

Disconnect all fish tank gadgets (i.e., water filtration systems, UV lights, bubblers, and heaters) and keep them in a box.

Pick all decorations from the fish tank (i.e., rocks, wheels, hideouts, fake plants, and other ornaments) and keep them in another container separate from the electronics.

Step 3. Empty the fish tank.


Siphon the remaining water from the fish tank. Alternatively, you can scoop the water out with a small pail large cup. You can also tilt the aquarium to drain the water. However, be careful when tilting the fish tank to avoid breaking it.

Remove the substrate, too. We recommend pouring the substrate into a strainer or sieve, especially if you have gravel.

Pick all loose debris, such as leaves, twigs, and other objects. Set aside the substrate.

Step 4: Clean the aquarium glass.

You are now ready to get hard water stains off aquarium glass. We will explore four methods in this section.

1. Use a scraper or razor blade


This trick is effective only if you have modest white residue on the aquarium glass or if the buildup is not too hard.

An algae scraper is best for acrylic or plexiglass fish tanks. It would be challenging to use a razor on these materials without scratching them.

Scrape the white residue off the fish tank surface with caution to avoid defacing the glass. Wet the residue with water to facilitate easier removal.

2. Use vinegar.


Vinegar is the best and most economical DIY aquarium glass cleaner for removing white residue from fish tanks. This is because it’s a weak acid that can break calcium carbonate’s chemical bonds, allowing you to remove the scale easier.

Fill a spray bottle with vinegar and spray it over the white residue. Leave it for 12 to 15 minutes, and use a damp cloth to wipe the whitish buildup. Use a scraper or razor if the residue is too stubborn.

Pro Tip: Try adding isopropyl alcohol and cornstarch to the vinegar-moistened white residue before wiping it off with a cloth.

3. Use rock salt and a sponge.


This method only works for “fresh” or newly formed white residue on fish tanks. Hence, timing is crucial. We recommend checking the white residue first to see if it is still soft.

Wet a sponge with clean water and sprinkle some salt. Salt crystals will adhere to the wet sponge surface and make it easier to work with.

Rub the sponge’s “salted” portion over the white residue. Add more rock salt to the wet sponge after every few minutes or so.

4. Use pumice stone or sandpaper.


Use this method to remove limescale from a fish tank only if all else fails.

For the sandpaper technique, cut the sandpaper into small pieces and carefully sand or smoothen the white residue off the fish tank.

For the pumice stone method, moisten it with vinegar and scrub the pumice stone against the white residue.

Be careful when using these methods because you might damage the fish tank glass.

Step 5: Finish up


Rinse the fish tank with clean water. While you’re at it, clean all the decorations, accessories, and electronic gadgets as well before placing them in the tank again.

Fill it with water, but leave ample space for the reserved water. Check the water quality parameters, including pH and temperature. Vinegar is acidic. So it might upset the water’s pH balance.

You might add a pH stabilizer or water conditioner to optimize water quality.

Return the aquatic plants, fish, and other livestock. Enjoy the view.

What is the White Stuff on My Aquarium Glass?


The white stuff on top of fish tank lid could be one of two things: “limescale” or “salt creep.”

Limescale contains calcium carbonate, magnesium, and other soluble ions (i.e., electrically charged particles) and is common in households with hard water. These white spots on fish tank glass form in freshwater aquariums.

Meanwhile, “salt creep” contains crystallized salts, such as sodium chloride (NaCl), potassium chloride (KCl), and sodium sulfate (Na2So4). As the name suggests, “salt creep” only develops in saltwater aquaponics systems.

Regardless of chemical composition, “salt creep” and limescale follow a similar development in fish tanks.

Heat moves water vapors from the fish tank, evaporating the water molecules but leaving behind other elements or minerals.

These “hard” or “heavy” minerals clump onto each other, forming an ugly white film on top of fish tank units.

Tips to Prevent White Residue in Aquarium Glass


Preventing the ugly white haze on aquarium glass is easy if you understand how limescale or salt creep develops. Consider the following tips.

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  • Be mindful of low humidity levels because they can hasten evaporation. Water in the fish tank evaporates to “balance” the low moisture level in the air. Adding a humidifier should help.
  • Monitor the fish tank water temperature to prevent unmitigated evaporation. Ideally, it should be between 75-80℉. However, as the specifics will vary depending on the species, you should keep track of which threshold is the best for yours.
  • Add distilled water to the aquarium when you notice its level reduce. This trick only works when topping off the fish tank, not during water changes.
  • Invest in a high-quality water test kit to monitor the fish tank water’s pH, alkalinity, hard mineral levels, and other parameters. It should give you a head start on whether to clean hard water stains on fish tank lid.
  • Consider installing a water softener to address hard minerals in the water. However, please check with your aquarist or veterinarian if softened water is suitable for your fish.


For instance, tropical, ornamental, and exotic species do not do well with soft water.


Learning how to clean aquarium glass white residue is as straightforward as cleaning a fish tank. The only difference is you have a specific purpose for cleaning the aquarium – remove the whitish haze on the fish tank surface.

Vinegar remains a popular option, although the razor-scraper technique might be more effective for not-too-hard limescale buildup. The rock salt-sponge trick is your go-to for fresh limescale, while the sandpaper-pumice stone method should be your last resort.

Also read: Easiest ways to clean a betta fish tank