First grow

The timeline is slightly messed up but its pretty much there. I need to go back and and all the nutrient ratios also but wanted to just get some pics up for now. I'm 3 days into the 11th week of growth, as others have stated this auto seems to take its time (sour orange), the OG kush seems to be about a week behind that! I've been getting some tip burn and some light brown patches on my sugar leaves and I'm not sure what this is. I gave PK for a couple of weeks to both plants in about week 6 & 7 and after about a week after that they exploded, the orange a lot more than the OG. It seems now the orange has platau'd loads and the OG is having like another wave of growth if that makes sense!? I water every 12 hours to make sure the coco stays moist, I PH the feed (now at 350-400ppm to see if it stops tip burn) to 5.5-5.8 and keep the tent a steady 45% rh and 27-30c . The run off is coming off at 450 ppm and 6.3 PH. I've read that this isn't always a great indication as to the PH of the plant, and also the run off can contain salt buildup so its hard to tell how much the plants are eating. Other than the tip burn they seem fairly healthy so I don't know if I should ride it out for another few weeks and see if I can start the flush before any issues start or try mess with the feed again...maybe its locking something out, I've not added any calmag for a good while as I read it's not really needed for flower but if the coco is taking it all who knows. Any help, advice and knowledge in regards to growing these or other autos in coco with liquid nutes is much appreciated.