A very low F/M and long sludge age or a chronic toxicity can cause pin floc condition. Pin-floc is also associated with denitrification in the clarifier
I have seen pinfloc caused by a switch from hydrated lime and soda ash to liquid caustic in a softening clarifier. UF ahead of RO removed the pinfloc in this municipal wastewater treatment system.
Shearing can be caused by an impinging device, like a centrifugal, progressive cavity or positive displacement pump. There are non-impinging devices on the market.