Bleach is one of the safest and most effective methods of disinfecting an aquarium prior to initial setup. Many aquarium keepers are afraid to use bleach because they fear its potency. However, bleach is perfectly safe if used correctly. We use bleach for disinfection because it is one of the most effective chemicals we have for disinfecting. It is commonly used in US hospitals and is recommended by the Center for Disease Control. Bleach, or sodium hypochlorite (NaClO), is also safe for the environment. It breaks down very quickly, leaving behind mostly salt and water. Because it is a strong disinfectant that breaks down quickly into harmless byproducts, it can be used to disinfect baby and pet toys, aquariums, and is even used to disinfect our water supply.
When purchasing bleach to clean an aquarium, use only regular bleach such as Chlorox Regular Bleach or an equivalent. Do not use bleach mixed with detergent. Detergents leave behind dangerous residues that can be fatal to aquarium fish.
Using typical household bleach (which typically already has 5% bleach), mix 9 parts water to 1 part regular bottled bleach in a container. I like to store it short term in a spray bottle purchased at my local hardware store. Keep in mind that lye breaks down pretty quickly, so only do small amounts at a time. Never store bleach in a bottle that you have previously used with other chemicals.
Here are six simple steps to disinfect your aquarium with bleach.
1. Clean any debris from the aquarium with warm water and a paper towel.
2. Spray all surfaces of the aquarium with the 10% solution you just made. I like to do this in my bathtub to contain any overspray. Sanitizing outdoors is also a good option.
3. After spraying all surfaces, let the aquarium sit for 10-15 minutes. Bleach is a corrosive chemical and can cause damage to your aquarium if left too long. Do not allow it to sit for more than 15 minutes.
4. Rinse well. When you’re done rinsing your tank, rinse again just in case.
5. Allow the aquarium to air dry completely. This will help ensure that the bleach solution has broken down into harmless byproducts.
6. Once your aquarium is set up, fill the tank with water and dose with a good aquarium water dechlorinator.
Aquarium gravel, decorations, filters, and heaters can also be bleached using the same concentration of bleaching water. You can spray them or soak them in a container depending on what you are cleaning. Be sure to rinse all bleached items very well and allow everything to air dry completely before putting them back in the aquarium. Please note that metal oxidizes quickly when exposed to bleach. As mentioned above, never allow the bleach to sit on the item for more than 10 to 15 minutes, and be especially careful with metal items.
IMPORTANT SAFETY INFORMATION:
Bleach can be very dangerous if inhaled or swallowed. May cause moderate to severe damage if contacted with eyes or skin. It can also cause discoloration or corrosion of some materials. Review the safety information on the bleach bottle before handling it.