Ph issue in rockwool or what am I looking at?

These girls been in veg two months, no problems at all. Just got into 5 gallon air pots with mini rockwool cubes. I use gh line for nutes. Noticing this weird deficiency or issue. Very sporadic on where it is. You'll see it affected a whole branch basically and is barely visible anywhere else. Is this a pH issue a deficiency? I have not seen any bugs at all but the holes are what throws me off
I am ready to put them in flower but I would like to figure this out first. Thanks for any and all help

Veiw of the whole plants

Have you been checking the ph of what you are feeding your plants and what the runoff is? Looks like a ph problem to me but testing would tell you that

mjinc said:

Have you been checking the ph of what you are feeding your plants and what the runoff is? Looks like a ph problem to me but testing would tell you that

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Just checked it on yesterday's watering. Ph going in was 5.7 and run off was 6.2-6.4 on multiple plants

TrichomeChaser said:

Just checked it on yesterday's watering. Ph going in was 5.7 and run off was 6.2-6.4 on multiple plants

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That seems about right. I would continue with the calmag in low doses for the time being.