Doesn't look like any kind of hair algae I have ever seen. Some species of brown (and other types) of algae have a chemical within that makes them unpleasant to eat. Have any of the snails I have sent you begun to eat this stuff? If the snails haven't it might be worth trying to use a Chiton, which eats all sorts of nasty stuff. Limpets are good too.
To fix an outbreak problem, (especially with
brown algae- an item that is never an animal's first choice, even when it is the kind they will eat in my experience), you may have to get a crew that is overrated for your tank- forcing them to eat the nastier stuff to survive. After that you would have to feed your fish more so they snails could scavenge, or trade some back to your LFS.
However, I think at this point you are best off trying to reach your hand in the tank, perhaps during a water change and remove as much of it as you can. Afterwards use a toothbrush, (clean not used), to brush off the remainder from the rock. If their is debris in the tank afterwards, (their should be), use your fish net to skim through the water to collect whatever is there. Your filter will get the rest.
Repeat this process, whenever you are looking at the tank and can't help but think that stuff is ruining the visual appeal of your setup, and I guarantee it will be done by the new year. If it is in a bad location try using plastic tongs, which you can pick up at the dollar store. Use the net with the tongs for best results.
After the tank is clean you must make sure you have a proper maintenance crew to prevent future outbreaks. To maintain the tank it is important to get the right cleanup crew. Yours is currently too small for proper biological cleanup, and that may be some of the problem. There may be some others reasons such as phosphates or silicates in your water, etc...
If the following eat the hair algae they would be the best to get for your problem:
Dwarf Planaxis and Cerith- to clean your substrate
Nerites, Chitons and Limpets- to clean the rocks
Let me know if the Ceriths and Nerites eat this stuff at all.
If you begin to get desperate, try blocking the algae's light. By cutting a paper plate to size and placing it on the cover of your tank over the algae you will rob it of its energy and weaken it. The rock underneath isn't getting the light anyway, by the looks of how thick it is.
