Please DO NOT mix cheap yellow brass with proper 85-5-5-5 marine bronze below the water line. This is the result of a home center quality yellow brass hose barb when mixed with an 85-5-5-5 marine grade bronze elbow.
Yellow brass is nearly 40% zinc 60% copper and the zinc becomes the anodic metal. Dezincification, the eating away of the zinc in the fitting, can occur rapidly and is usually identified by a pinkish coppery colored brass that should have been yellowish gold. If not caught in time the item could potentially catastrophically fail and potentially put a boat on the bottom.