Leaves curling on sides - hydro

Hi,
 
I am trying DWC hydro out and having some trouble.
 
I have a young guajillo pepper plant with leaves curling up on the sides.  It has been this way for several days.  I have two others which are not showing signs of a problem like this...
 
I am using Flora Duo mixed to a PH of 6.3, mostly part A mixed to 360-400ppm and it stays 68-70F. 
 
Maybe it is calcium deficiency?  I am using tap water at about 90 ppm so I haven't been using CaMg+...  but maybe it isn't hard enough.
 
I had been higher ph water (adjusted to ~7) until the first true leaves showed up, so maybe it was the shift in PH.  I wasn't sure if that was too big of a jump.  Next time I will use more acidic water the whole time.
 
It seems like there is a bit of cotyledon "sun" burn too from my LED lighting.  This plant is the closest to the center of the light.  
 
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Any ideas?
 
Thanks

usually its advised to do 5.5 - 6.0 ph hydro, otherwise i dunno.
 
the cotys will turn color and fall off after a while that's normal.