How To Clean Aquarium Glass White Residue – A Few Tricks Of The Trade

Are you wondering how to clean aquarium glass white residue without harming your fish?

Or do you want to clean your fish tank to get it ready for a craigslist sale?

Or did you buy a tank off of craigslist and need to clean it up?

Whatever the case may, let’s discuss just what exactly is that white residue.

What Is That White Residue?

The white residue is actually calcium deposits (and/or salt minerals for saltwater fish tanks) that is a natural mineral found in water. In the worst case scenario, this residue can be limescale which is a little more difficult to remove.

As your tank water evaporates, the minerals are left behind. Hence the logic of topping of your aquarium water with freshwater in saltwater aquariums to refrain from adding more salt and minerals that could lead to lethal levels.

Do not use household cleaners as they are toxic to fish!

How To Clean Aquarium Glass White Residue – A Few Tricks Of The Trade

White Vinegar

If your tank is used, chances are that there will be some calcium or mineral buildup on the aquarium glass. This is the best time to clean your tank now that it is empty. Using non-toxic cleaners, such as white vinegar, ensures you don’t have to worry about the fish that will be inhabiting this tank.

Apply the vinegar directly on the calcium (lime deposits) and let it sit there for a few minutes. The vinegar will naturally break down the deposit making it easier to scrub off. Washing your tank with a baking soda solution should neutralize any traces of vinegar.

You may have to repeat the cycle of scrubbing to get stubborn deposits off but it is well worth the effort to make sure your tanks view is unobstructed by nasty residue.



A High Quality Algae Scrapper

I was fortunate enough to come across the ADA Pro Razor (The 20th Anniversary Model). My Local Fish Store (LFS) happen to have it in stock that day of my visit.

Without hesitation, I immediately purchased it have not regretted it one bit. I am a huge of of Takashi Amano and his whole line of products so the decision was fairly easy.

It is, by far, the best aquarium glass scraper I have ever owned. It works awesome and and it flat out looks incredible.

On the other hand, if you are looking for something cost effective and don’t mind putting in a little  elbow grease, a standard razor blade should do the trick.



Mr. Cleans Magic Eraser

How To Clean Aquarium Glass White ResidueDepending on the severity of your white residue problem, this may or may not work in your case. Calcium deposits that have been sitting there for a longer period of time will be tougher to remove.

The good news is that the magic eraser effective for cleaning your aquarium glass in general.

If someone can attest to this as being harmful to fish, please let me know in the comments below. In all my years of using this to clean my aquariums, I have not seen any detrimental effects to my livestock.


Worst Case Scenario:

If vinegar does not remove all the white residue, then you may be dealing with etching.

Glass becomes etched over time and this is often seen in older, or used tanks. Which is why it is not uncommon to see tanks sold on craigslist to be unsightly with so much white residue.

It usually happens along wherever the water line was in the tank. Nothing will take off etching, short of actual polishing. Glass polishing is very time consuming, and probably not worth the time and effort considering how cheap you can get another used tank for.

On the bright side, etching does not show if it’s wet. So if you fill the tank with water above or to the line, it will not show up while in use.


As the saying goes, an ounce of prevention is worth a pound of cure.

Limit the amount of water evaporation that occurs. Glass tops help and are the main contributing factor into limiting evaporation.

Reducing the airflow over the top of the water will also help, as some people use fans to cool down water temperatures.

If you have the luxury of adding a sump, a constant water line in your display tank also helps in preventing calcium build up at the top of your aquarium. I did this with my 12 gallon long aquarium and was happy with the results.

Daily or weekly maintenance including scrubbing or scraping the water line areas help to prevent buildup.


Don’t let unsightly white residue prevent you from buying a used aquarium. Used tanks can save you hundreds of dollars. All it takes is a little bit of hard work to get them back to looking brand new.

I hope this guide has been helpful in providing a few pointers on how to clean aquarium glass white residue.

If you’re looking to buy a small tank that is perfect for your desktop office, be sure to check out our Best Nano Aquarium Guide.

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