new growth cupping badly, please help

[dodacky]

Hi Guys,
started out with just 1 plant a couple of weeks back all the top new growth the leaves were cupping up badly, I had really low humidity (less then 20% but now up around 45% temps 26-28 degrees C) and the exhaust intake was directly above and thought maybe it was sucking her dry. well I moved the intake a bit and it perked up for a day or 2 then got worse and now a few other ladies are showing the same thing.

I am unsure where to even start, any help is greatly appreciated.
could it be insects? I had spidermites early on in the grow and sprayed a few times and haven't found any more, ive checked affected leaves with loupe and cant see any insects.

thanks

 

[_tessarecting]

Oh jeez, this could be russet mites, you need to get a 60 or 100x scope and look for eggs. Do a search for what they look like. When confirmed implement the ipm regemin in my broad mite thread. Ive had great success with it. Good luck.