I bert,
look here for your curling leaves
Marijuana Plants Problems - Yellow Leaves, brown spots, nutrient shortage etc.
Scroll down there is a good troubleshooter there.
Possible heat stress but photos as always would help

In my excecution chamber, the leaves that recovered eventually died after greening up, the damage was already done. New growth should be speeding up by now. Don't worry about the growth that was there in the tent but keep an eye on the new growth, I am certain that you won't have defficencies with ionic soft water at the strength of the solution you are using now. A tower fan blowing across your plants wouldn't hurt either.

Keep us in the loop

Subzero :smokin: