That is correct that silt has been suspended into the water column.

Diffusers have a tendency to build a hole around themselves when in opperation. During the shut down time, these diffusers could have been covered back with the silt that they pushed out of their way duing the summer.

I would shut the system off, pull the diffusers up and let the silt settle out. Lower the diffusers back in and go though your normal start up timeline.

Unfortunately for you, I have only seen this happen a very few times. You may have a large amount of organic muck to assimilate before you reach hardpan or sand.

If your silt does not settle out within a week, contact me and I have some suggestions to expedite that problem.