ProPack's Kronen Holding Tank Treatment - 4 oz. Six Pack PT#KHT000 6 treatments per box. 100% USA Made Product. Kronen Premium Holding Tank Treatments use a potent combination of naturally occuring microorganisms that specially engineered to break down and liquefy organic materials. Soft subtle Frangrance Destroys odors before they start. Formaldahyde FREE and 100% Nature Safe