Topsoil is usually buffered to a lower ph, (6.0 or so) so I'd contact Scotts, and see what their Topsoil is buffered to.

Miracle Grow All Purpose directions are for a 10 to 14 day period. (1 tsp per gallon) Half strength (a weekly dose) would be approx 1/2 tsp per gallon. When I use it, I use 1/4 tsp per gallon, twice a week.

6.5 ph ingoing is a tad low before adding nutrients. Try bumping it up to 6.8 or 6.9ish before nutes. 6.5 ph is fine for plain waterings, though.

Too young for a true calcium or magnesium def. But unsulfured molasses at 1/4 tsp per gallon, once a week usually doesn't hurt, but is mostly unnecessary. In mid to late flower, I give 1 tsp per gallon, once a week.
Rusty Trichome Reviewed by Rusty Trichome on . Possible Magnesium Deficiency? My 2-3 month old clones are experiencing yellowing of new growth. The yellowing is localized on the perimeter of the leaf, leaving an arrowhead-shaped darker, healthier green in the center of the leaf. Researching google, I diagnosed this as a magnesium deficiency (whether I was right or wrong) and followed the directions posted under the sticky "epsom salts = not miracle cure)," spraying the leaves (yesterday and today). The condition seems to have become worse since applying epsom salts. My Rating: 5