my live rock
 

they are turning into big peices of green alge what can i do?

How old is your Tank?
This can be expected in the early days of the tanks life.

Things you can do to combat Algae.
reduce feeding (feed smaller amount wait until fish have eaten everything and add alittle more)
reduce photo period
make sure water being used for top up and changes has no phosphates
Vacuum it or pull it out by hand.

I spent about 9 hours one day pulling hair algae it has never returned.

good Luck
Jason