Red Veins Appearing on the leaves

hi there first timer, yes actually that's a symptom for a problem, always checking your stems for redness is a good idea and a key to diagnosing almost any problem before it occurs, thinkof it as an early warning signal. What the problem is is that you're overwatering slightly each time you water, probably because you're watering just a bit too soon not too much, wait 12 to 24 more hours and the plant will bounce back.... because you caught the problem quickly. If the leafs keep pointing down you need to add an additive to fix the root system like enzymes , humic acid or beneficial bacteria . Hope this helps ! 🚀

Thanks guys I've got the temps at 27 degrees Celsius lights on with lights of right about 17/18 maybe need to try a heater in their

It could due to genetics but I'm leaning more toward it being because of low temps at night I see your around 66 degrees and about 82 in the day that's a 16-degree swing, you don't want the difference to be more than 11 degrees.

Try to bring your temps down a smidge to 25-26°c and i see you are growing in coco, add some Cal-Mag and watch them take off!. Don't forget to keep that Ph in check ✌️🏼