Thanks for coming back to me so quickly. I’ve answered the following:
Problem: strange downwards curling/twisting of some leaves
Medium/grow method: biobiz light mix
Feed: and supplements used: only a bit of biobiz root juice so far.
water source: tap
Strain/age: Dutch passion auto critical orange punch, hybrid.
light used: originally 300w full spectrum LED, however it was a cheap light bought from amazon so I swapped it for a 75w full spectrum LED from a reputable horticultural light supplier.
Climate: small tent 100cm high x 40cm x 40 cm. Exhaust fan. Temp 25 degrees C day time, 18 degrees C. Night time. Rel humidity around 45%.
Any Additional info: (How long problem has been happening, things you've tried already, ect.) I think that changing the light has helped as the newest growth looks fine.