Since you already did 'something', i'd wait to see if it worked before doing more. If you just used plain water, still might want to spray with some weak h2o2 or your silver bullet root stuff but don't double dip on a disinfectant treatment until you see the first application's results.
the answer is based on whether or not the slime regrows... Staining without slime or stink is usually from the fertilizer. turning a little tawny isn't a major concern.
organic material added to the reservoir will rot, which is generally bad for hydro. That's not quite the same as everything that falls under the "organic" marketing term. it's not the same as the term from chemistry. The marketing version is not a scientific term.