Decorative coral, rocks and aquarium decorations often can be cleaned with hot water and gentle scrubbing or by suctioning the debris away with a gravel cleaning device. Sometimes to get rid of calcium buildup and crusted-on algae that forms on rocks and decorations, you need to use an aquarium safe cleaning product.
Remove Aquarium Algae
Fill a bucket with a nine to one mix of water to chlorine bleach. For example, mix 9 cups of water with 1 cup of bleach.
Soak the aquarium rocks and decorations in the bucket of cleaning solution for about 15 minutes.
Scrub the rocks and decorations with a soft-bristled brush or sponge, then soak the decorations in clear water for 15 minutes.
Let the aquarium decorations dry completely before putting them back in your aquarium. Expect it to take at least two days for the items to dry.
Remove Aquarium Calcium Buildup
If the rocks and decorations are coated with a crusty layer of calcium buildup, distilled white vinegar is a natural cleaning product you can safely use on items for your fish tank. It takes some time to start working, but white vinegar softens the crusty layer so you can wipe it away.
Use the white vinegar as a straight soak for several hours, making sure everything that is encrusted with calcium is submerged.
Scrub the rocks and decorations with a soft or medium bristled brush to remove the calcium layer.
Rinse off the vinegar with cool tap water, then let the decorations dry completely before using in the fish tank.
Test for Safety After Cleaning
After cleaning aquarium rocks, especially if the rocks are ones you found in a river or field, test to make sure the rocks are safe for your pet fish. Soak the rocks in a bucket or pan of fresh water for 24 hours, then test water's pH levels to make sure the rock is not raising the pH levels.