So I have about 2.5 gallons of honey and decided I would try my hand at some mead. I had a guy I work with offer me his fermentation bucket and carboy incase I decided brewing wasn't for me I wouldn't be out too much money. I bought a wine whip, airlock, bungs, nutrients, energized, yeast, and starsan. When he brought me his containers they had been set outside to dry and left for some time under a birch tree. The bucket had some black stuff inside and all over the inner part of the lid. Idk if it is mildew or something from the tree. I removed gaskets and cleaned everything with 1 step cleanser and plan to use starsan before brewing. The bucket seems to have some staining from w.e this substance wash would the cleaning I gave it be sufficient or should I avoid using it? Sorry for the long winded post over what may be a simple question but I wanted to provide accurate information.