failed strawberries?

Hello. I have a problem. My vertical tower presently hosts strawberries. Over half of them have failed in the net pots-literally rotted leaves and stems while the others have thrived. All net pots receive the nutrient solution which is 5.5-5.8. The rotted plants were mostly located toward the top of the tower. I did notice I was having some spillage from the top net pots, so I created little plastic shields (visor-like)over the top of the net pot. That helped. I have built the tower as directed on the video. No modifications, except that I could not find a blind-stop for the drip guard, so I sent away for a 5/8"x5/8" square pvc rod. More expensive, but necessary. Also, the plants were sent to me from a nursery-you know bundled in a rubber band with the bare root exposed. They looked dried out and half dead, but revived nicely in their own net pots. Is it possible for some net pots to receive too much water and damage the plant? These strawberries are outside now that it's summer. The changes in temperature fluctuate about 30 degrees here in Wisconsin. 80 daytime-50 at night. That means the water will get cold as well. I'm grasping at straws here...any help is appreciated for you that grow your towers outside.