The skimmer is reacting to the Herbtana in the water, you will have to collect the stuff in skimmer cup, and remove from tank, if you just let it flow back into the sump, the same thing will happen...romove as much as possible. If you skimmer has a hole to drain cup (my reef octo has) attache a pipe to it into a bucket - then you wont have to wait and empty....it will calm down once the meds have cleared the water...