I posted here a few days ago about yellow/brown tips. I was told she needed some nutes, which I did but it has since gotten worse. My ph meter needs calibration and the hydro store had no buffer solution. Could it be ph? nute lock out? or should I continue with just water? I don't think heat is an issue as it's under low watt cfls for now. I have no idea what to do. Help please and thank you.