Black colour flims on leaves

[benzz]

Hi to all.Most of my plants are having black colour layer of flims on the leaves and also fungus like stuffs at the side of the leaves.Have try using hand to clear it off but unable to remove them.

Really appreiate if you guy could advise what is this problem and ways of removing them.
thanks

[barmby]

Tank parameters? Pictures will help too...

[benzz]

hi,thanks for the reply.anyway have cut & remove the Black colour leaves.will see what will happen next.