Put driftwood in for the royal. They need it. You may not see it but they need it. Also, offer them veggies a couple times a week. I've found that zuchinni is the easiest. Your other plecos will love it too. I put mine in (I give half a zuchinni at a time and then I cut that in half long ways and skewer it on spoons so they stay sunk to the bottom) at night and within minutes they look like a ball with pleco tails sticking out in every direction. Trust me on this as I learned the hard way with royals.