My ph was low for a few days in DWC. What harm would this have done? 2 of my babies have rust spots on the lower leaves(older) and some yellowing from tip towards stem veins too. The other 2 babes look great.I followed the GH nute guide for amounts desired. I am now into my 6th day with same nute solution. ph now maintained at 5.8 doesn't seem to rise or drop much after a 24 hour period it may rise to 6.1. What are the rust spots and yellowing? My roots are still inside the pots with hydroton.