Claw is from excessive Nitrogen. I know you feel your ppm are low but in all honesty, growing sativas in a hydro setup is just begging to be frustrated. Some are way beyond finicky.
They are very challenging plants to grow correctly. Clawing will effect your yield. Anytime you have an imbalance or plant stress it's going to effect it (not dramatically).
Maybe it's the roots, I haven't done a straight hydro setup, but I highly doubt it. I would try to get root temp down anyway.
I have had plenty of clawing - and always with my more sativa dominant plants.
While I'm just now entering flowering, this grow has been really breezy so far other than this little bit of clawing. Chocolope is apparently a good sativa strain for beginners, and takes well to indoor. Definitely understand the imbalance issue. Something interesting is that I have one plant that is a monster because I did no pruning or topping. It's a perfect specimen. I wonder though, if it could be out-competing the others for a particular nutrient or even oxygen.
I still am strongly doubting nitrogen toxicity. There is no nute burn anywhere, leaves are a little on the lime-green colored side if anything. Also there is zero progression of the claw once it appears. Mature leaves that have been clawed for weeks stay as they are.
I've thoroughly inspected my roots and they are pristine--not a blemish anywhere. Though, if they're a little lacking on oxygen I can imagine them looking healthy but still not being as productive as they could be. I'm leaning towards a little oxygen deprivation on this one. Also, my res temps dropped by a couple degrees since last week and new growth has shown less clawing--but we'll see how those leaves mature.
Actually the higher temps might be effecting the pH of your solution somewhat. I'd guess you'd ruled that out though.
Yeah, my pH is extremely stable. I have to top-up on nutrients before I need to adjust my pH, and my ppm drops about 15 per day.
Lots of good things to think about, thanks again for the responses.
