a few thoughts of my own. Maybe:
The flush was not done excessively enough, not enough water.

Or is it possible that feeding them 1/2 strength after the flush may have been too many nutrients? I think i read somewhere that the plants become more sensitive after all that water running through them.

Or, one thing that concerns me is the moisture that is in the space. I am using a black plastic tarp to manipulate the photoperiod to 12 12. When i take it off in the mornings, a lot of condensation is covering the inside. The humidity can reach 80% in the tank, with the tarp on. This being in a VERY dry part of the country. Although i could see this causing problems, i know a few folks with identical setups and they dont run in to high humidity issues.

Lastly could be that after the flush it rained for three days. So the pots were pretty moist for about 5 days. I put them up on blocks as weedhound once suggested that to help speed drying. But when the air is filled with so much moisture there is nowhere for it to go, especially at night with the plastic sheeting on it.

These could also have nothing to do with it, maybe they are just still K deficient?:hippy: