seahares almost always die after a short period of time. In a 14 gal it might eat some of the algae but when it dies it's just going to pollute the tank creating more problems. In a small tank like that this should be easy to manage with water changes.
Kalapnath makes a good point though, algae is never a problem it's always a symptom. Something is contributing the nutrients to it.
+1, MR should have like buttons or something.Your tank is new... Most new tanks develop some sort of algae, most of the time it's hair algae. Get a clean up crew (snails) and it will be gone soon.