What Has Happened To My Plants?

[crmpicco]

I have an issue with some of my plants in that they seem to grow black hairs from them. I have uploaded a couple of images below to show the problem.

I have picked a few out, but this shows a big cluster of them.

Why do they do this? Is it harmful for the health of my fish?

 

[PrairieSunflower]

It is algae, it is not harmful.  Depending how many plants you have, I tend to find the easiest way to get rid of it is to pull up the plants and scrub them under tap water... then the bit that is left is easily eaten by your shrimp... they don't seem to eat it when it gets stringy like that.

 

[DerpPH]

it looks bad. try to lower your photoperiod to 4 to 5 hours or even black your tank out for a while.
 
Its BBA and it is hard to get rid of since no fish or shrimp eats the stuff. Dosing with excel might help