Did you check the online schedule and start following it?

What does the new growth look like? Old leaves are old news, and they don't heal. They'll keep fading.

How are you testing runoff ph? If you're not using a ph pen, likely your numbers are off.

You'll want to keep the ingoing water between 6.3 and 6.8. I aim for the upper-end, (6.8ish) since adding nutrients drops it further.

6.1 ph is a tad low, not a tad high. (unless you're in coco or running hydro)

Like I already mentioned, it might well be overwatering. Provide pix, and perhaps we can see...