My new Sea Hares aren't eating my hair algae. Wrong species?

[edmond]

I got two sea hare's from Live Aquaria to help combat my hair algae problem (along with water changes, lowering light time and adding phosphate remover). But its been about a week and they have barely touched the stuff. I see them slither over it, but they aren't eating it.

Did I get the wrong species of sea hare for eating hair algae?

I bought two of these for my 50 gallon tank:
Saltwater Aquarium Invertebrates for Marine Reef Aquariums: Sea Hare Sea Slug

 

[joy13]

They don't eat hair algae from what the description says " If regular feedings of Caulerpa are not possible, it will need a supplemented diet of parboiled lettuce and dried kelp."