mine is not going to grow that big since he's in a 1g tank
This is not true. A pleco may not reach full size (20") in a smaller tank, but they will always end up over 10" regardless of how small of a tank you stick them in. Well, that or dead. Your choice. A pleco's growth may be stunted by a small and inadequate tank, but not dwarfed to a point where it can just indefiantely survive in such a tiny tank because 'oops, id's getting awfully tight in here, maybe I should just stop growing.' Doesn't work that way. Its like telling a human baby that it can no longer get any bigger because you don't want to ever let it out of its crib to give it any more room. It's just not going to happen. It's already too big for a 1 gallon, and it's still not going to stop growing because of it.