Wow thats some impressive growth.I don't know on all geos but mine are pretty slow growers. Seems like the only things the grew quick in this tank so far are the delhezis, moke, ctenopoma. My Dels both shot up to 8-9 inches with in 2.5-3 months from 3"ers. I was freaking out! they have leveled off but are still the two biggest fish in my tank.
What kind of geos do you have?