...I've honestly found it hard to properly diagnose a cannabis plant when problem occur since nutrient toxicities, deficiencies, and pH issues can go hand in hand...especially when your using additives, it
can be hard to point out the culprit.
...I will tell you this much...the miracle grow soil has time released fertilizers in it that open with waterings....the wetter your soil is, the faster those fertilizer capsules will open...the fertilizers that are released are synthetic salts that are acidic on a pH scale, and thus lowers your soil's pH when they open.
...I personally would pick better soil, true organic soil that will only require transplants and waterings.....such as Fox Farm's Ocean Forest, Roots Organics, exc...
...you can simply start your seedlings off in very small containers with a 'light soil', such as Fox Farm's Light Warrior or Promix (seedling heating mat will help germination)....after a couple weeks, transplant into a slightly larger pot (say 1 gallon) filled with a stronger soil such as the FFOF, RO....after 3 weeks or so, you could then transplant into a slightly larger pot (say 2 gallons) of FFOF, RO.....you can follow this process all the way through harvest and you'll get superior quality results that when dried/cured properly can compare with the best of growers....using water only throughout the whole grow.
...do not add salts, chlorine, or any preservatives to your water, this will dehydrate/kill the microorganisms in the soil.
...I've created a thread titled, "soil food web gardening, with compost teas" you might find informative....here's the link --->
https://www.rollitup.org/organics/427826-soil-food-web-gardening-compost.html