Distilled water has a pH of 7 and is considered neutral. Anything over pH7 is considered alkaline (AKA base).
If the alkalinity is too high it will destroy the aluminum. (sodium hydroxide has a pH of 14 - It is extremely caustic and will destroy aluminum.)
Baking soda (sodium bicarbonate) is a weak base. (pH 8)
Pool pH up, or washing soda (sodium carbonate) is a stronger base. (pH 9.6)
Amonia is a moderate base. (pH 11)
A mixture of;
distilled water (as a neutral solvent)
amonia (to obtain an alkaline pH)
and Dawn dishwashing liquid (to reduce surface tension)
would probably be an ideal solution.
Good luck
