Howdy growell, What is the growing setup and do You have any photos of the system and plants? I have had, a few times, seen a froth or foam in my hydroponic system. It has appeared only when the temperature of the water gets too warm (at or over 70° F) and some sort of microbe starts to grow, I assume that it is a microbe due to the unpleasant odor. When the water temperature is kept below 69° F, the 'foaming' does not appear. I try to keep the temperature down by regularly changing out ice bottles.