DWC M-L Strawberry Lemonade Second Grow

Howdy, So it’s day 40 today, left and right have been topped for the last time a few days ago, I think the middle bush has another 3/4 days before she’s ready for her last topping. So far I have done 3 complete res changes averaging about 12 days between each change. There has been some signs of deficiency on the largest of the group. I think it could be down to two things, she is the closest to the water filling cap where I add PH down and nutrients to, so her roots are getting hit with it before it mixes in the rest of the res. Second it could just be that the water was depleted of certain nutrients as I stretched it for 2 weeks and as she’s the biggest, she felt it the most... Main thing is there is no signs of it getting worse. I’m having to add about 6-10 litres of water per day. Some HST again on day 39 with some cling film over the bends just in case of any splits. I think I’m going to veg for another 5-10 days, they’re about 1ft 2 inches tall at the moment... I installed the second light on day 39, so everything is ready for flip day. Both are 4200k bulbs and will remain so until week 3/4 after flip day. I will then change them out for 3200k bulbs when the stretch is complete. A 30w UVB bulb will be added to the grow in the final 2 weeks of flower.