how can I get greyish-white marks off my shower tray ?

[dedado]

I live in a soft water area and use shower gel, not soap in the shower. The white plastic shower tray has a film of greyish white gunk on. I've tried cif and elbow grease with a mildly abrasive sponge and atiny bit may have shifted but I may be imagining it.

Ideas please on how to get the gunk off and how to maintain it.

Bump

some stains will dissolve into some plastics. I am surprised CIF did not take it off as it is milldy abrasive. I suppose you could use barkeepers friend but it will eventually wear away the surface.

Try spot-testing to try to work out what it is.
E.g. a bathroom spray cleaner and a green or white nylon scourer will remove soap scum. For some reason shaving foam leaves persistent marks even in soft water.
Vinegar will remove limescale (even though you are in a soft water area)
White spirit will remove most grease marks including body lotions (rub and off on with kitchen roll, do not rinse down the drain)

Thanks, I'll try those ideas