Turtles are an integral part of the environment and can make wonderful pets. Their habitat is not a spotless paradise. Turtle shells will often accumulate algae over time. Although the algae itself might not pose a threat, it may mask one. Inspect your turtle regularly.
Give Your Turtle a Bath
Soak your turtle in a tub of warm water or hold your turtle underneath running water.
Gently rub the shell with a soft washcloth. This will remove most of the dirt and algae. Small bits of the shell may flake off in the process. This is part of the normal shedding process.
Scrub your turtle's shell with a soft brush. An old toothbrush works quite well. Lightly scrub away the larger portions of algae but there's no need to scrub the shell completely clean.
Check the shell for infection after most of the algae is removed. Soft spots, or spots that smell rancid, are an indication of shell rot and should be treated by your vet as soon as possible.
If no problems are detected, you may then apply an application of turtle shell conditioner. This specially-formulated conditioner helps to revitalize dry or brittle turtle shells and can be purchased at pet stores.