When new decorations are placed into an aquarium they look great, but over a period of weeks and months they begin to get covered in brown and green algae; they no longer have that crisp, clean look and are in need of some cleaning.

• Remove the decorations from your aquarium

• Place in a clean, soap-free sink

• Use an aquarium sponge to wipe away the built up algae

• Use a small soft brush (such as a clean toothbrush) to scrub tight spots

• Rinse thoroughly

• Return decoration to your aquarium

Clean Aquarium Decorations with Bleach

Sometimes hard algae will form on your decorations that normal scrubbing won't remove. To clean these decorations requires a diluted solution of plain bleach with no additives (just sodium hypochlorite as the active ingredient). Fill a clean food-safe 5 gallon bucket with 4 gallons of freshwater and add 2 ounces of bleach.

• If possible, use a powerhead (small submersible water pump) to circulate the water.

• As you know, bleach can take the color out of carpet and clothes, so dress appropriately.

• Remove decorations from the aquarium and place them into the bath. It will take time to dissolve the built up algae; for that reason the length of time to leave decorations in the bath is determined by how dirty they are.

• The key is to not leave the decorations in the bath longer than necessary since long term exposure may cause discoloration.

• After 30 minutes check your decorations if they appear clean remove them from the bucket, rinse them thoroughly with fresh water. If they are still dirty, leave them a bit longer and check every half hour until clean.

• A toothbrush can be used to scrub off any dirt and algae left in the cracks and crevices of the ornaments.

• Let them air dry preferably in the sun for a couple of days. 

Decorations can all be cleaned at once but it is best for the livestock if you only clean 25% to 50% of your decorations at one time. Removing all the decorations for a few days may stress your fish, especially shy and territorial fish. Many people have two sets of decorations and put the clean set into their aquarium when they remove the dirty set to be cleaned. After they clean the dirty decorations they should be stored in a safe place free from insecticides or other life-threatening chemicals. Fish may seem a little stressed when decorations are replaced, but this is normal. You are totally changing their comfort zone. After a few times replacing decorations they become more relaxed with the process.