Over the weeks after cleaning my bath tub, there appears slowly a
greenish scummy deposit - feels like soap scum but its green. My first
thought was the green 'Shield' soap I was using was the source of the
color. But I stopped using colored soap (ivory now, its pure white),
and still the green returns, regular as clockwork.

I changed my shampoo to and orange one, and still the green continues.

I washed the tiles thoroughly, and cleaned the curtain, and still its
coming back.

So I have narrowed it down to one of the following:

1. Leaching out of the copper piping. Nothing appears in the other
showers and sinks, however, its just this one.
2. Leaching out of the tiles - they are indeed pale green, but come
on!
3. As my wife just put it, something green is leaking out of me. I
feel pretty healthy though!

Any ideas?