Is Bleach Safe for Cleaning an Aquarium ?

Clorox Beach
Always dilute bleach with water (and nothing else) before using it to clean an aquarium. Mike Mozart/Flickr/Creative Commons

Broach the subject of using bleach to clean an aquarium, and a heated discussion about safety is sure to follow. Is bleach safe or not? The answer is yes; when used in proper concentrations, bleach is safe for aquarium use.

For those who gasp in disbelief at that statement, here's another fact you should know: bleach is the CDC's (Centers for Disease Control) approved method for sanitizing drinking water following disasters. Yes, many thousands of people have partaken of bleach-treated water and it caused no health disasters. Bleach is a perfectly acceptable chemical to use for disinfection purposes, provided it is used correctly and in the proper proportions. Bleach, after all, contains a concentrated form of the same chlorine that is used to disinfect most urban drinking water. 

Having said that, when used in the wrong concentration, or if combined with other chemicals, bleach can be hazardous. So which is it--is using bleach safe or not? If you follow the rules, bleach is safe to clean your aquarium, equipment and even plants. It will safely and effectively disinfect glass, equipment and accessories in your fish tank. 

Bleach Safety

There are a couple of critical rules to be aware of when using bleach. Follow them, and you don't have to worry about harming yourself or your fish.

  • Don't mix bleach with any other chemicals. That includes soap, aquarium chemicals, or other cleaning products. Use only bleach and plain water.
  • Don't use bleach in concentrations higher than ten percent.
  • Don't soak anything in bleach for longer than fifteen minutes.

How to Bleach

Prepare a 10% bleach solution by mixing nine parts water with one part bleach (9:1)  in a clean bucket or container (example: mix 9 cups water with 1 cup bleach). Submerge the aquarium items in the solution and soak for ten to fifteen minutes. If cleaning an aquarium, simply fill the aquarium with the 10% bleach solution.

Following the soak, drain off the bleach solution, rinse the container and refill it with clear water. Place the items in the clear water and allow to soak for another fifteen minutes in the fresh water. Rinse well yet again with clear water, and allow everything to air dry completely. They key here is in the thoroughly rinsing. If rinsed correctly, all residual bleach is neutralized and removed. 

What to Bleach

You can safely clean most non-porous items in your aquarium with bleach. That includes:

  • Aquarium (either glass or Plexiglas)
  • Non-porous aquarium equipment and parts, such as the filter hoses
  • Plastic plants (bleach is fantastic for killing off algae on artificial plants)
  • Gravel and rocks

Avoid using bleach on silk plants and brightly colored gravel or decorations, as it will fade them. Also, avoid wood and other porous items that can soak up and retain the bleach.

Mineral Deposits (Lime)

If the primary cleaning problem is white crusty mineral deposits, don't even bother hauling out the bleach. Instead get out the vinegar--it works great! Commercial cleaning products advertised for cleaning aquariums are wide sold, but really, all you need are these common products already in your kitchen cabinet.