i do not think they will go more than 10". they stay relatively small i guess. about the algae eating, they do eat algae but they need more than algae at this size.
I JUST PICKED UP 2 OF THE SCARLETS, 2 OF THE THUNDER ROYALS, AND ONE OF THE ALL YELLOW RUBBER...ALL LOOKED GREAT AND RICH MADE SURE THEY WERE READY BEFORE I TOOK THEM....