Ph problems

Usually ph in a nutrient mix will rise over time. There can be two causes of this. Firstly, nutrient salts can interact with one another causing ph to drift upwards. Ph down especially drifts over time, so I make corrections the next day after mixing. Make sure you are not noticing significant salts floating as flakes in the mixture. Another factor can be bacteria. Bacteria feed on the same compounds (eg. Nitrogen) as plants, and a nutrient res is a great place for them to make a home and multiply. Bacteria will then cause ph to drift upwards. In high number you will notice them via their smell (hard to describe, slightly fishy maybe). This can be limited by keeping the res as sterile as possible (cleaning if surfaces between mixes), keeping it somewhere cool and dark, and by adding something hydroponic safe that kills bacteria such as h2O2/hydrogen peroxide. I cannot keep my nutrients under 70f, so I add 2.5ml/gallon h2O2 32% and it limits the ph drift. Just be careful if you track down concentrated h2O2 as it can cause chemical burns if not handled carefully. Happy growing 👍🌱