i have had my tank set up for over a year and then suddenly overnight on the top of the water there are loads of little green bits. the water looks totally clear but on the surface there are lots of green bits - whats happened.
What kind of green bits?
Have you added anything recently to the tank?
Have you changed anything or doing anything different?
What are your water stats?
What size tank and what fish do you have?
What is your maintenance routine?
Any chance of a pic?
Looks like the filter needs clearing I had this problem with my Aqua one which had a ripple bar on top and I evenually found it had a bar between nodules which I had in the wrong position.
Worth a try .
I added and external filter then and it soon solved the problem