I bought 4 True SAE and 2 Chinese SAE, and after just one day I noticed that the hair algae was reduced to about half but after that day there has been no noticeable hair algae reduction. The true SAE have been either lazying on the ground or looking for food on the sand nowhere near the hair algae. The Chinese SAE are almost the same expect they lazy on the glass.
Am thinking of providing an additional food for the SAE to stimulate their appetite. I am currently feeding my fish "Spectrum Grow" by new life and "Biofish food" by Aquarium Munster, I toggle between them during the week. I am thinking of using h20 stable wafers as they're large enough to be noticed and large enough not to be gobbled quickly by the neon tetra.
The algae problem is discussed here