pH migrates like geese in the fall

[MootPointBlank]

Just thought I'd update this thread and mention that the GH Up/Down proved to be MUCH more stable and potent than the pond and aquarium pH adjuster that I was using before. I discovered that the foam was due to a fungicidal paint coating the inside of the res lid. Nutes are clear now and plants are taking-off. Thanks MJ Passion! MPB