Copper galvanized pipe corrosion

I need to pipe a hot water recirculation system for my hot water heater. I need to T into the drain spigot on the bottom. I will use a short galvanized nipple, galvanized T, then a spigot. The other side of the T will be copper. How can I keep this from corroding? It already has this system installed and has very bad corrosion. Do they sell 1/2 copper nipples, T's, etc.? I could also go with a dielectric union at the top of the T and at the spigot. What are my options here?

Thanks