I have 10 plants and I keep taking digital readings of the pH and it is coming up with a 5.5 reading at the bottom of the 5 gallon pots. When I take a digital reading from the tops of the pots they are showing 6.6. I am experiencing cupping and twisting of the leaves. I have eliminated all other factors for the cupping and twisting...(temp in grow room, distance of lights to the plants and humidity) Does anyone have any tips? I want to balance my pH back out to 6.2-7.0. Should I use egg shells or put a base substance in my water for feeding? I would prefer the process be organic but if worse comes to worst I will use any method possible to improve my current situation. The photos of the plants in the chopped water bottles are my new plants that are experiencing the same thing.