I'm not disagreeing with anyone but will throw this out there. I use rain water, which comes in at around 6.5, then add my nutes, my pH drops to 4.x. I would be concerned that constantly using 4.x pH'd water would eventually buffer my soil to the acidic side.
Are any of the ProMix HP users nuting up with rain water? If so I would be curious to see what their final mix pH's at.
Are any of the ProMix HP users nuting up with rain water? If so I would be curious to see what their final mix pH's at.