Ionic® Grow Hardwater is purposely blended to be more acidic than standard Ionic® Grow. A more acidic nutrient solution will neutralise bicarbonates on its own. This in turn reduces the amount of acid needed to control the pH in the reservoir and thus reduces the possibility of acute phosphate accumulation during the vegetative growth stage of your plants. It is also formulated to take into account the minerals, such as calcium, that are usually present in hard water.