New Growth Yellow Centre

Hi everyone, this is my first grow and it's been a real adventure! This blueberry plant has been growing for about a month and it seems to be doing OK but I've always had yellowing in the foliage. At first I thought it was a calcium deficiency but nothing really changed when I added cal-mag.

I am using GH trio following their coco chart so:
1/2 tsp micro and gro /gallon
1/4 tsp bloom /gallon
1 tsp calimagic /gallon

using a 600w MH and 3 gallan air pots with coco/perlite

I have started upping the watering to once a day with about 20% runoff. I am thinking there might be an excess of P or K. Any suggestions?

I should also of mentioned I use tap water, let it sit out for a day or so, add my nutes and PH it to about 5.7/8. Usually closer to 5.7 since I've seen my run off come out a point or 2 higher.

Ph could do with raising to 6

Other than that they look OK, if anything slightly over fed

New growth is always paler, but try reducing the feed

BTW you should look at using the Lucas 6/9 formula and drop the GH Grow