Thanks for the replies.
I did visit plantgeek and there is some help. Thing is it doesn't fit exactly to any of the algae types. From what i made out watching closely after doing a
water change, gravel vac etc, it
is the dust settling on the plants after being stirred up. Whats happening afterwards is that the mold/algae forms.
Hmm, i'll have a try at my
LFS and see if they know anything. As i said it's not all the plants that are affected mainly the hairgrass and hornwort. Basically the plants that can trap the dust...
As for starting afresh, unless it is harmful the fish i'd rather not. Emptying a whole 67gal, whew! lol, but of course if it has to be done, it has to.