Overwatered Hydroponics?

I know this may sound strange but is it possible to overwater plants that are growing hydroponically? I have been at this a long time and I don't know what is going on. The ph and nutrient levels are all correct and the plants are a healthy green with solid root structures, but the leaves on two out of six are wilting and showing signs of what would be overwatering if it happened in a soil setup. The only thing that I can think of that could be causing this is that the clones are in 3x3 rockwool cubes surrounded by clay pellets that almost touch the bottom of the hyrdrobin. The bins can take 3.5 gallons of water, but the fill line is at two gallons which I try to observe. I think that the rockwool cubes are staying too saturated and I actually need to add less water. Any suggestions because these are strains that I created myself and want to mother and really don't want to lose them. Thanks!

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Stop watering the rockwool cubes. You are right. Your plants are not getting enough air.
I had the same problem with rockwool.

If your on a drip then just hit one corner of the cube for 30 min twice a day and let the rest stay dry.

Little tip, I found by starting clones in rapid rooter plugs and then gettin the 3 inch rockwool with the hole and setting the plug in the hole it helps keep the upper root system dry. The roots can take water 24/7 in the hydroton but rockwool pulgs up.

Thanks for the reply. I suspected that they weren't getting enough air and have been keeping the water level fairly low since then. They are in a 3 gallon plastic tubs with airstones attached to pumps. I used the smaller 1 inch cubes for a long time and never had a problem. I tried the 3x3 and notice better initial root growth early on, but developed this issue as they got bigger.

You can over saturate rock wool and starve the roots of oxygen pretty easily

mine is doing the same exact thing, i have mine in 2 gallon buckets each has its own 2 seperate air pumps and stone, under a gallon of water, they were fine up until 4 wks old and roots grew longer, then the leaves turned up and some grew spots and yellowish, i have correct ph and no nutes, so i know thats what it has to be, looks alot like yours here, and my lights are 5 inches away, all cfl, so no light burn, there was so much bubbles it was constantly soaking the rockwool, i just went to half a gallon of water maybe, lol, i hope like crazy mine shape back up