Bumblebee snails are mainly for detritus/carion and more of a predator than a beneficial tank cleaner. For nuisance maco algaes, a good snail would probabley be a margarita snail. As with all types of algaes, the best method of eradication is removal combined with natural predators and ensuing you use a pure water source. Most will ignore out of control algaes or be ineffective at eliminating them if too long. It is very important to keep it manually cropped as well....
Cheers
Steve