Reversing 2 x 4 evaporator pan

[clw]

Does anyone reverse a 2 x 4 pan? I have a 2 x 4 pan with ports on opposite ends. I have never reversed the pan. I am seeing a lot of niter crystalizing and burning on the bottom of the pan by the drawoff valve. What are the detailed steps of reversing?

Obviously empty the pan?
Scrub and clean the pan?
How often?
Will this make the syrup lighter?
Does the boiling look different when there is niter buildup?
Is there any way to do some filtering as the sap flows thru the channels to syrup?

I would appreciate any comments and opinions.

Thanks for your help.