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Removal of dark rings in fermenters

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  • Removal of dark rings in fermenters

    hello
    we've been noticing some dark rings forming inside our fermenters. (Non-organic build up of some sorts?)
    we've tried some concentrated phos/nitric acid washes that seem to lighten up the stains but not remove them.

    what is a good strong concentration to use?
    Contact time?
    Temperature?

    we have some straight nitric acid, would that be better to try?
    (i know its nasty)
    thanks

  • #2
    Biofilm (I think)

    I believe that the answer is chlorinated caustic. This comes from a brewery in MN, and they said that they were able to get rid of that scum by adding bleach to the caustic cycle. I've tried it, and the key is to make sure you're at the appropriate caustic concentration and you add a solid dose (sorry, but I didn't measure it specifically).

    One note: chlorine will not corrode stainless steel in a basic environment, so it's cool with the caustic. However, you really need make sure you're rinsing it all out of there, because if there is chlorine in your tank when you switch to acid, you're going to have problems.

    Best of luck,
    Bill

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    • #3
      Used bleach with caustic when at Rogue, worked fantastic. Didn't require separate passivation step after caustic either (I don't remember the details as it was explained to me at the time, sadly). Caustic/bleach wash, rinse, santi. done... Careful when mixing the stuff though, you get a nice exo-thermic reaction! Be ready to get it into the tank on top of the hot water ASAP when you mix it.

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      • #4
        beer and milkstone remover from Enerco

        I inherited some tanks that had not been acid washed over many years and had tons of stone build up (that looked dingy brown). All of the nitirc acid CIP's in the world did nothing for it. My chem guy explained that even though the build up is mineral (inorganic) it is bonded to the tank organically. The acid can't seep through the build up enough to dissolve it or break the bond. I used beer and milkstone remover in conjunction with my usual caustic dosing and it came clean in one CIP at 120F. Now acid CIP can keep the build up down but to remove it, it needed the stone remover. I'm not sure what's in it as they keep it a proprietary secret but it definitely works like a charm.
        Cheers
        Jay Stoyanoff
        Brewmaster
        Plattsburgh Brewing Co.
        Plattsburgh, NY

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        • #5
          Originally posted by Bham Brewer
          Careful when mixing the stuff though, you get a nice exo-thermic reaction! Be ready to get it into the tank on top of the hot water ASAP when you mix it.
          Why not just put the hot water in the tank, add the caustic, then add the bleach?

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          • #6
            That sounds like Calcium Oxylate build-up. Its caused by reaction between caustic and Co2- Remove with acid wash and/or 'beerstone remover' and make sure you vent + rinse tanks well before cleaning.
            Brewmaster, Minocqua Brewing Company
            tbriggs@minocquabrewingcompany.com
            "Your results may vary"

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            • #7
              If you have an Ecolab supplier nearby (they usually supply restaurant industrial chems) ask them to ship you some Pipeline PLX. It's a chlorinated caustic that we find works wonders.

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