My friend is currently having a similar problem. He is using a drip system with grodan stonewool grow cubes. He will have the pH just right and not 4-5 hours later its back up to over 7.5-8.5. He is getting irritated because he knows this is stunting his plants growth.
sandman1982 Reviewed by sandman1982 on . pH problems - What to avoid? What products/components commonly used in a hydro system cause the pH to spike? What are your experiences? What should you avoid or not do? My understanding is that food grade plastics are better. And I've noticed a lot of people use Rubbermaid tubs. Unfortunately, where I live that brand is not available. There are currently no plants in my new setup, but after adding tap water at around 5.5 (yellow) to the system and running it for a few days it has a ph of at least 8 (blue). My first Rating: 5