Can You Use CLR on an Aquarium

Cleaning stains in a fish tank can be exhausting and frustrating. Hard stains take forever to remove, even if you use vinegar while cleaning.

Nevertheless, you can’t let the stains build up in an aquarium. At least, not in one you intend to admire after a rough day!

So, what can we do then? Stronger reagents have a good record against the toughest of stains.

CLR is among the reagents touted to make your work easier when dealing with hard stains. Keeping that in mind, can you use CLR on an aquarium?

Well, I don’t recommend using CLR on an aquarium. Especially an aquarium full of fish. CLR, short for Calcium, Lime, and Rust remover, is very toxic to humans and fish. It should not be near a fish tank full of fish. 

Can You Use CLR on an Aquarium?

Furthermore, CLR  is terrible news for sealants on your fish tank. It will eat away the sealant leaving you with a leaking tank. It is one more reason to avoid using it.

What about in an Empty Fish Tank?

If you are a native of online fishkeeping communities, you might have stumbled upon fishkeepers claiming that they use CLR on their empty fish tanks without any loss of fish. Interesting, right?

I think you should not use it on any fish tank unless it is completely unavoidable. If you have tried everything and the water stains are not gone, you might need a stronger reagent. CLR fits the bill, but you should ensure that you use it safely.

Before we talk about using CLR, it is essential to mention that the keyword is an empty fish tank when using the reagent. It would be best to take everything out of the fish tank before CLR comes into play.

An empty fish tank
An empty fish tank on a wooden stand.

How to Safely Clean an Empty Fish Tank Using CLR?

Extreme situations call for extreme measures. Sometimes, we must put our feet in the mud to get what we want. After everything is done, the results will be worth it.

The argument here is simple: since we use diluted CLR on coffee pots, we can use it on fish tanks. If we can drink coffee from pots cleaned with CLR without any harm, fish will be fine if we are careful about it. That makes sense, right?

As you think about that, here is a step-by-step process of cleaning a tank using CLR:

  • Dilute CLR with water. Mix warm water and CLR in a 1:1 ratio.
  • Use a cloth or sponge to apply it to the Glass part of the fish tank. Do not let the solution touch the tank’s frame or lead.
  • Leave the solution for around 2 minutes before rinsing it off. Rinse it off as much as possible- 8 to 10 times with cold water. You can always rinse the glass more times to be thorough.

You can repeat the process until the fish tank is sparkling clean.

  • Dry the fish tank and use a water conditioner to eliminate the remaining chemicals.
  • Fill the fish with water and let it cycle before you add fish. Adding fish into the tank after cycling will reduce the chance of losing your fish. It is something you should do if only to keep your fish alive.

Additionally, you should use your aquarium test kit to check whether the vital parameters in the fish tank are stable for fish. The tests will guide you on what to do to guarantee the safety of your fish before you add them to the fish tank.

Aquarium Test Kit
Test Kit

Frequently Asked Questions

Q. Is CLR safe to use on rubber?

A. No, not according to CLR product pages.

Q. What cleaning products can I use on a fish tank?

A. You can use bleach, CLR (or other glass cleaner and lime removers), chlorine remover, and dedicated aquarium cleaning products such as Tetra Aquasafe Plus. Double-check any product before using it to clean a fish tank.

Q. Can I use dish soap to wash an aquarium?

A. Big No. Don’t ever use dish soap or detergent to clean an aquarium. It is impossible to rinse away soap residue. Any trace of soap you leave behind is harmful to fish.

Q. Is it safe to clean my fish tank with vinegar?

A. Yes. You can even use diluted vinegar on a tank with fish. While at it, we recommend using white vinegar over any other vinegar.

Q. Which is better, CLR or vinegar?

A. Depends on what you want to achieve. Both are great products. Vinegar is safer but less effective on tougher stains than CLR.

Q. Where do you put the fish when cleaning the tank?

A. Temporary fish tanks. They can be a bowl, cup, basin, etc. It is great to have a dedicated temporary fish tank. However, if you don’t have one, use anything that you don’t wash or clean with soap.

Q. How do you remove stubborn algae from fish tank glass?

A. Refer to our article on the same!