Sounds like a psuedomona sp. Ya might wanna toss your LK or anything else that's got much carbon in it, if this is something that keeps happening. Psuedo colonies are usually pretty sensitive to disturbance, so I suspect you might be re-introducing from concentrate stock.

Psuedos are Gram-negative, and therefore kind of a pain in the ass to eliminate w/o root damage. However, they usually aren't that competitive in most enviornments ( Thank God, cuz otherwise there wouldn't be anything else) .

You could try a couple of things to control- Bump any one enviornmental condition a little bit ie run the res a little cooler/warmer, or pH .2 higher/lower, or ec up/down- differant bacterial populations will be most competitive under differant conditions.
An enzyme product will help ( hygrozyme, sensizyme,cannazyme etc) by lysing the cellular wall of Gram+ bacteria.

Clean the rig well between crops using a sanitizer ( H2O2 works well and is cheap enough, as well as requiring no rinse- just let it all air dry).

Ya don't run Physan thru irrigation systems because large farm systems almost always run to waste, and Physan will kill ALL the bacteria exposed to it- rendering farmland incapable of supporting crops, killing rivers, that kind of thing...

Hope this helps.

Using a subtillus inoculate will usually prevent serious slimecoat issues ( voodoo juice, subculture, etc) as both psuedomonas and subtillus are surface colonizers, and the subtillus inoculates will crowd out the psuedomonas.