The answer is the same as you would any other shower frame. Firstly it is important not to use abrasive cleaners such as Cif Cream Cleaner. Instead, spray on an undiluted white vinegar solution. This will break down mineral buildup and any residue from the aluminium. Remove the excess with a soft sponge. Once dry you can finish off with a light buff of car wax applied to a soft cloth. Yes car wax, this will restore the shine beautifully and prevent water spots from appearing.