First, I see this is your first post....Welcome to APC!! I think I see a few threads of hair algae on the crypt, but I suspect you are talking about the nice growth of Black Brush Algae (BBA) on the gravel. Some people have had success getting rid of BBA with higher CO2 levels, I used Seachem Flourish Excel per the information in this thread to get rid of mine: http://www.aquaticplantcentral.com/forumapc/algae/3806-flourish-excel-got-rid-all-my.html It is a long thread, but excellent information. BTW my post is on page 20 #193, with how I got rid of my algae problems!
I get that type of algae (BBA) when my CO2 and/or nitrates drop too low. Dose mose nitrates. Also, get a syringe and squirt Excel directly onto the algae. This will turn the algae pink and it will be dead. Make sure no to OD Excel in your tank, especially if you have inverts, as I have noticed they are more sensitive to extra Excel in the water column.
I've also noticed that once it starts, it is extremely hard to get rid of completely. If you're hardware in the tank is covered, look up how to do a dip in a bleach solution (i believe the standard is 1 part bleach 10 parts water) and dip you're hardware, then rinse thoroughly before putting it back in the tank.