Help needed

Okay I'm sorry this is a really common misconception among soil growers.. I'm autistic so bear with me here.. Part of your problem could be from you flushing.. when you flush or water to run off the medium of all available nutrients you are leeching or removing all intake from the plant.. This could be a start of your problem... it really is a balancing act like a juggling game keeping all the balls in the air and trying to understand at the same time.. I had a very time with growing at first...

That looks like it could indeed be a deficiency... The lower part of the plant will be sacrificed first if there is proper circulation but it's a bit more complex.. when the circulation of the plant has enough stuff in it your top leaves will stay healthy when there is something off she will loose top foliage.. Unless you've made a change.. Ie flushing or something.. You should not be seeing this. I'm a little different sorry about the sentence structure.

2ml coca canna a 2ml coca canna b 0.5 cal/mag to 2l water ph today was 6.3

Thanks for replies, I did test the run off of my water today. Sadly I already gave him a feed, he has 0.5 cal/mag 2ml coca canna a, and 2 ml coca canna b , the run off from this was 6.6 any advice there would be great, I did have nute issues around week 3 or 4 and damaged a few leafs but they haven't got any worse, seem to be flying threw ok until this week when I've had the issue on these 3 leafs

You look to be having a few problems, your leaf tips turning brown can be from nutrient burn or light stress, the yellowing of the leaf looks to be manganese deficiency with your leaf tips turning brown leaf turning yellow and yellow veins . You should flush your medium and check your run off to make sure your not locking out any nutrients. Hope that helps and good luck to you

Lacking in potassium 🌱👍