Amano shrimp (Caridina multidentata) are the most effective algae eater in the hobby — larger than Neocaridina at 4–5cm, and relentless on hair algae and leftover food. Named after Takashi Amano, who popularised them in planted aquascaping.
They are far more tolerant than other Caridina: pH 6.5–7.5, GH 6–10, and comfortable anywhere from 18–27°C. They will not breed in a freshwater tank, as the larvae require brackish water to develop — so populations stay exactly where you set them.
Worth noting they are bold feeders and will out-compete smaller shrimp at feeding time. Buy UK-bred or UK-acclimated stock rather than freshly imported, which often arrives in poor condition.