is ther any known member who uses aliminum sheet for waterscapes so that the metallic brushed effect of the meta allows for shimmering reflections from still waters, I think thick acryilcs are the paints used, obviously the metal has to be de-greased prior to use.

Hi Mickwhitehill! I've never painted on Aluminium before, but there is a basic thing to consider to achieve the "metallic" effect you're trying to achieve. Most Acrylic paints (though not all) are opaque which would block any metal from showing through.
if you want to have a go at this, the best way would be to use only transparent colours (or as transparent as the system allows, and don't use any white, as this will certainly block the metallic show through.

Perhaps consider using Acrylic Inks, which would be a much more transparent system.

As far as de-greasing the aluminium, it probably is a good idea, as the acrylic may struggle for good adhesion on the metal surface.

Good luck and very best wishes,

Steve Williams
PA & RSC Wigan area