pH DOWN Overview pH control is essential in a hydroponic system Plants in hydroponic systems function best with a nutrient solution pH of between 5.8 up to 6.2. Growth Technology has a full range of control solutions, essential for the proper management of nutrients in hydroponic systems. These products are manufactured using the purest and most concentrated sources available. Bottled in black and red – the internationally accepted packaging colours for aggressive liquids. Full compliance with all health and safety regulations. Growth Technology pH DOWN contains orthophosphoric acid (H3PO4). The concentration is 81%, which is very strong so handle with care. Some other products on the market are considerably weaker, so check the concentration before buying. This is a very dense liquid and should feel much heavier than water. Health & Safety: This liquid needs safe and careful handling: Always wear gloves and eye protection when handling aggressive liquids Always store in locked cupboards KEEP AWAY FROM CHILDREN pH UP and pH DOWN should be diluted before use – please see the link on the side of this page for Instruction on Handling Aggressive Liquids.