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How Do I Clean My Aquarium? Part 3: Cleaning the Glass or Acrylic Panes

The name of the game when cleaning the glass or acrylic panes of your aquarium is preventing scratches. The best way to do this is by properly using the right tools.

Scratches can easily occur from blades, rough sponges, or gravel getting stuck in between a cleaning tool and the pane. The tendency of a substance to be scratched is related to its hardness.

The Mohs scale of hardness is a universal scale of mineral hardness by which substances are rated by the mineral they can be scratched by. Acrylic aquariums are made of cell-cast acrylic and have a hardness of 3 out of 10 on the Mohs scale. Glass aquariums are made of high or low-iron silica glass and have a hardness of 6 to 7 out of 10.

Cell-cast acrylic is manufactured pane by pane when unreacted acrylic is poured between two sheets of glass separated by a gasket to determine thickness of the acrylic pane. This method results in 92% clarity and great resistance to water erosion.

Glass panels or panes are either regular silica glass or low-iron silica glass. Low-iron glass has around 90% transparency compared to around 80% of regular silica glass. This is due to 0.01% ferric oxide in low-iron glass compared to 0.1% in regular glass panels.

Low-iron glass is not harder or softer than regular glass, it is only more transparent. With less of the green hue from the lower iron content, thicker panes of low-iron glass on larger aquariums allow for a much higher quality viewing experience of the contents of your tank.


At a 3 out of 10 on the Mohs scale of hardness, acrylic scratches much easier than glass at 7 out of 10. If you opted for acrylic over glass due to its lighter weight and higher transparency, you’ll want to ensure you keep it in the best condition by using the right tools to clean it.

While glass is harder than acrylic, it can also be scratched. Natural gravel can contain mineral pieces which are harder than glass. If they are caught in between the glass pane and a tool or sponge, they can easily scratch the glass.

Stainless steel is often used as a glass-safe blade for algae scrapers. Stainless steel has a hardness on the Mohs scale of 6.5. If the blade becomes bent at the corners, it could scratch some glass which falls between 6 and 7 on the scale.

Regardless of the tool, for the most part, there is a glass version and an acrylic version. Algae scraping blades for glass are made of stainless steel. Blades for acrylic are made of plastic. Sponges for glass are more coarse than the softer sponges made for acrylic. Most magnet cleaners allow for soft acrylic safe inserts.

A magnet cleaner is a tool which uses two magnets, one on the inside of the aquarium and one on the outside. Both magnets are encased in a protective plastic casing. The inside casing and magnet has a piece of felt or thin sponge and sometimes a scraper blade attached to it. The magnets are placed on either side of the pane and as you move the outside magnet, the internal one with the felt and scraper moves with it. This allows you to wipe down the viewing panes without submerging your arm in the aquarium.

There are several popular brands of magnetic cleaners. Make sure you purchase acrylic safe inserts to use between the magnets if you have an acrylic tank.

As we go over the methods for cleaning the panes, keep in mind the tool you’ll be using will depend on the material your tank is made of. Be sure to only purchase tools that specifically mark the material they are designed for.

  • Steel blades with handle

  • Plastic blades with handle

  • Course sponge with or without handle

  • Soft sponge with or without handle

  • Ammonia-free glass cleaner

  • Microfiber cloth

  • Magnet cleaner


Before you begin vacuuming your gravel and removing water, and before you replace your filter media, I recommend cleaning the viewing panes of your tank. As you scrape off and clean the algae that has accumulated, it should end up in your filter or in the water column. Then you can remove it with your media replacement and water change.

Begin by wiping down the front pane. You can either use a hand sponge, a sponge with a handle attached or a magnet cleaner.

Start at the top of the pane and wipe from left to right top to bottom. Leave an approximately one inch margin at the corners and bottom of the pane. Repeat this process for the two side panes and as much of the back pane as you can safely reach without disturbing equipment, plants, and decorations.


Next, you’ll clean the corners and bottom of the viewing panes. I do not recommend using a scraper, plastic, or steel to scrape the corners as the integrity of the silicone can become compromised. Even if you have a glass tank, I recommend using a softer sponge, with or without a handle, and gently apply pressure to the corners as you wipe up and down. You can then wipe up and down right along where the silicone meets the pane as well.

If the sponge is in contact with the silicone, apply less pressure with more passes. If you apply too much pressure, it could peel away older silicone.


After the front and side viewing panes have been cleaned from top to bottom and in the corners, you’ll want to clean around your internal equipment, if you have any. This equipment includes filters, heaters, powerheads, thermometers, etc., and is usually installed along the back pane. If the item is easily removed, like a thermometer, you can remove it, wipe it down, and replace it. If not, you can use a toothbrush or soft bristle narrow brush to clean next to and behind intake tubes, heaters, and powerheads.

I would also recommend using a bottle brush on the inside of your intake and output filter tubes after you shut your filter off for the water change. These areas can accumulate detritus and algae if they are not opaque.

Cleaning the Outside

Finally, polishing the outside of your tank is important to remove any water stains and keep the glass as clear as possible to allow the best viewing experience. Also, your photos will come out better with clear, polished glass.

First, spray a microfiber cloth with some ammonia-free glass cleaner. The glass cleaner must be ammonia free in case any residual aerosol gets in the aquarium. To prevent any contamination to the aquarium, spray the cleaner into the microfiber cloth from 5 feet away. Don’t spray the cleaner directly on the glass or acrylic. Then simply wipe the outside of the tank until it's dry and streak free.

A soft touch

Using the right tool to clean your aquarium glass or acrylic panes is key to preventing the overapplication of elbow grease. Combining the right tool with a soft touch and some patience will prevent scratches and damage to the silicone, keeping your viewing panes looking clear and transparent for years to come. It is possible to buff scratches from acrylic tanks, but glass is a lot more difficult. Preventing damage is much easier than removing it.

Be sure to keep up to date on the latest in aquarium cleaning technology. We sometimes get used to a particular method and forget to explore newer, easier options.

  • Boodleshire LLC 2022

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