Ask The Brewmasters

When I get this kind of inorganic buildup I like to use a nitric acid based product such as Ultra-Niter at twice its strength and then recirculate for multiple hours until its gone.   A new brewery I took over even had me run this cycle for 8 hours to remove all of the inorganics.  Make sure to always run a caustic cycle afterwards to neutralize the chemicals and then rinse really well.