I completely agree with HD Blazingwolf on balance. Re-evaluate your photo period/intesity and Fert. protocol.
I would suggest you:
A) Physically remover as much as you can.
B) Do a large water change 30%
C) Read the threads on this site about HO2O (Hydrogen Peroxide)
BEFORE you start any chemical warfare campains
D) Consider natural Algae solutions, shrimp, Fish, snails.