Is this light burn from my LEDS?

[ggotch]

had to go right back to the beginning to locate ph info,and indeed grow type and so might have missed a change or two.

ph should be 5.8-6.2,varying the ph to 6.2 will allow the cal to be taken up i think,if you are still down at 5.5ph then youll be locking out the cal i should think.

also im unsure what the theory is with using rockwool cubes,ive seen that coco growers dont let their grow dry out and wondering if you are,then perhaps you shouldnt?,pretty sure ive seen another rockwool cube grow somewhere here,perhaps find it n ask that grower whats what.

but for the most part from me i reckon your ph is too low at 5.5-5.7,and of course the usual "have you calibrated your equipment"