Bio·pH- Down it was specially designed for the organic farming sector. It is an aqueous solution of citric acid which occurs naturally in various citrus fruits, such as lemons. It can be used both during the vegetative and flowering periods, in every irrigation and in combination with any substrate or liquid product. Bio·pH- Down does not contain strong acids, which means that this 100% biological pH regulator does not harm the microbial life of the substrate. Keep everything organic in growing, from planting to harvest.