[flyingfrizzle]

Most marine tanks are made form 5052 (5000 series) aluminum. It is one of the most corrosion resistant grades of aluminum and yields higher strength than say 3000 series which a lot of AL stuff is made of. 5052 has more magnesium in it to aid in its properties. If you can find marine grade fittings that are 5052 grade or 5000 series you will have better corrosion resistance. A lot of fittings are 6061 aluminum and have good resistance to corrosion but the 5052 grade will be a better match if you could find them. I wouldn't be afraid of brass if that's what you had tho.