Spring cleaning is it really necessary every year?

[Angel]

prior to my bog and a better leaf netting ( installed last year) I would empty and give my pond a decent clean out.

This year post bog and post better screening for leaves not sure if i need to clean the pond or just blow out the bog.

and blow out the bog i mean its a 100g stock tank i added pipping to blow air out to aigate crap out (no pun intended )