I have to go with Bucks theroy(which is actually fact) that you should treat the algae instead of spending money on critters that will eat it. All you will do with algae eating critters is attempt to maintain algae and not rid the tank of it.
If you have an algae problem it is most likely caused by nutrient imbalance which should be taken care of. It will not only rid the problem of algae it will also improve the growth of the plants and give the fish a more stable enviroment to live in.
BTW I have 8 Caridina Japonica's in my 40 gal and all 8 have survived for at least 4 months!!! They do a good job at getting rid of green hair algae. But again you need to eliminate the problem and not just maintain it!!!