Many metals cannot sit side by side without corroding one another.
The further apart the materials are in the scale or series , the higher the risk of corrosion is.
Add in a conductive electrolyte like rainwater, as we do with every roof + rainwater system, and corrosion is the end result.
So avoid having copper roofs with rainwater running off into zinc gutters - for a worst case scenario!
Don't mix Cast Aluminium and Cast Iron Gutters. Replace the parts that need it with the same (matching Cast Iron components ) or replace the whole system with Cast Aluminium.
If you wish to discuss this further - get in touch on 0800 644 44 26 or email: Sales@rainclear.co.uk