Food for my Sea Hare

I bought a sea hare about 2 weeks ago in an attempt to control the green hair algae growth in my tank. I am happy to report that the algae has been completely wiped out however, I am now faced with a different dilemma. With no algae in the tank, the sea hare has nothing to graze on. The shop where I bought it from said that it will likely die. Can I give it anything else to eat? After the great job it did in my tank, I've become quite attached to the little guy. Help! :sad

Thanks for the advice. Unfortunately, it is all for naught. My sea hare died yesterday and it picked the worst spot in the tank to croak. I had to tear apart a third of the tank to get at it.