Its true that lawn mower blennies eat a lot but not only living algae - in my experiences algae tabs for algae eating catfish i a very good food for lawn mower blennies. In my aquarium they have eaten everything.
IMO - its a myth that you need to have a lot of algae before you introduce grazers. If you wait until you see a lot of algae with your own eyes - you have already lost the battle. You will need a ridicules huge CUC in order to win. The right way - IMO - is to introduce the grazers before you see any algae with your own eyes and if necessary supplement with supplementary feeding using algae tablets (for freshwater algae eaters). If you start to see algae - you just increase the CUC.
