I've got the same thing. If you stir up the bed then you stir up the useful bacteria there--which is worse IMO.
I think that is just algae on the glass. What I do if it gets too bad is take a long scaper and push is down the glass between it and the substrate.
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I prefer my substrates stirred but not shaken
Current Tank Info: 150gal long mixed reef, 90gal sump, 60 gal refugium with 200 lbs live rock
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