I do PWC
each week, yes. Detritus build up could also be from the fact that I dont have any more sand bed snails and only 5 or so hermits. The hermits spend their time picking at my rocks. Yesterday, I got a small fighting conch to help with the sandbed. After acclimation, he buried himself and is just staying still with one "eye" out seemingly watching everything around him rather than eating.
I need to start sucking the detritus out when I do my PWCs.