I already told you in another thread, watermelon plecos are one of few that are DI
-urnal. Meaning no matter what he will be out and about any time of the day. Plecos are constant grazers, so even if he gets fed, he's still going to be swimming around searching for food.
There's really nothing you can do, he's going to keep stirring up your sand, especially since he's a Di
-urnal. Hiding places won't change that either. Also, it takes plecos a few tries before they realize veggies and fruits are foods.
That being said, I'll gladly buy him from you. I haven't been able to find another one locally.