Time permitting, my schedule:

1) plants
Any nice day in spring.

2) bio filter
I run mine on slow flow all winter, start it up totally as soon as
water temp gets up to 45-50 and weather forecast says temps are going to
continue on the increase.

3) waterfall
See 2). I don't run main waterfall thru winter.

4 sludge cleaning
Fall. Unless not done last fall. ~ jan
~ jan/WA
Zone 7a