Blocking the column for mashing in still

[Armymedic.2]

Hello, 

    Being a startup on a very tight budget I have been mashing in the still (Bain Marie oil jacketed 100 gallon).   The mashing itself works great.   I cook my corn in the still, with  the manway open or closed but not latched, pump over to a jacketed fermenter to cool, and add malt.

 

What I am noticing though, is that the bubble plates and the inside sides of my column are getting a tarnish to them that is multicolored and relatively persistent.   Even citric acid with the CIP didn't clean it all off and I flooded the plates multiple times.   I think it is corn dust and corn cooking vapor/steam that is fouling the copper.       Removing the column is not an option while mashing as it is a 10" column and heavy as a bugger.    And I'm a one man crew.

 

My initial thought was to try and block the column off somehow while mashing.     Perhaps corking the drain holes in the first plate and filling the plate with water to create a vapor barrier at the bubblers,   or tin foil across the whole thing as best I can (which doesn't seem like it would work)    It means removing the sight glass every time which is a pain, but its better than having copper that isn't clean enough to do its job when I distill twice a week. 

 

Any suggestions on blocking the column that are better than my initial idea?   I know I'm not the only one mashing in still, so I figured Id ask.

 

Thanks for your time,

Keith