Tropica made some tests on algae eaters that says Cherry Shrimps are the next best thing right after Amanos, specially if considering their weight/size (and for me also more cost effective).
You'd need a boatload though, if you have more than a tiny bit of algae. I have quite a bit of GDA on rocks and wood in my shrimptank at the mo' (it actually looks kinda... good😵), and while its not spreading much; it isn't diminishing much either. And I have somewhere between 50-100 shrimp in a 45P 😀 They did clean the hair algae of the pinnatifida thoroughly, so there's that