Yeah, I know it's hard to tell, but what was the PH to your best guestamite?

And I certainly don't see any rot root in those pictures. The roots look nice and white. As you add nutes that will change over time so don't get freaked out about it when it happens. Especially with organic nutes. Where I thought I saw rot was where the Rapid Rooter was touching the roots the most, and I thought the stem right there looked brown and squishy. If it's not right now then don't worry about root rot. Roots look great, and they will really start bulking up soon with the new nutrients.