Biothane® is very easy to clean: a cloth dampened with water should do the trick. If you need a deeper clean, you can use a soft sponge and mild soap or detergent. Don't forget to dry it afterwards, including the fittings.
The hardware is solid brass, and it is normal for it to darken over time. With lemon juice or any liquid or powder metal cleaner and a dry cloth, you will leave it as new.
It is normal for brass to stain Biothane®, but with the deep cleaning that I am telling you about, you will be fine.
IMPORTANT: Biothane® is very resistant and is excellent for many features, but it is not proof against chewing dogs!
