Might want to add some fresh veggies to his diet, if you don't already use them... some deshelled frozen peas, zucchini (courgette), etc. These can really help you, and him have 'looser' poop.
Ultimately, plecos are poop machines. Gotta just accept it. If have have a pleco, you have a poop problem. Adding a powerhead can help, but mostly to move it to a single spot in the tank where it will be easy to vac out regularly (as Goat suggested).
Ultimately, plecos are poop machines. Gotta just accept it. If have have a pleco, you have a poop problem. Adding a powerhead can help, but mostly to move it to a single spot in the tank where it will be easy to vac out regularly (as Goat suggested).