Its just one plant. I should have just said the new growth was curling (some tops are close to light ,some not as close).

I use silica blast sometimes but don't have PH issues (not yet this cycle at least).

I have decided it must be a dehydration induced lockout because the roots look fine (at least the little nubs that stick through the smart pots). A friend of mine (a master grower by most standards) recommends flushing and suspects a lockout issue (He does not know about the up curl and burn yet).

I agree once a day sounds like not enough but I had soggy root problems last time so I switched to smart pots, added voodoo and ZHO to the regime and went to one watering a day. All the other plants look great so I`m sticking with it. Even the sides of the cloth pot are always moist so I suspect deep inside the pot the rockwool is still quite wet.

Update: Its been three days. Day one I just crossed my fingers. Day two I gave them a foliar with a dash of Liquid Karma. Day three, it has not gotten better and the smallest leaves (coming out of the very top of the bud) have developed burnt tips, that curl up. Some of the leaves have BOTH curls. Aggressive down curl that almost makes a closed circle but a sharp up curl at the tip. The up curl and the burnt area are EXACTLY the same area. WEIRD!

I'm gonna flush it tonight