Do they carry Happy Frog soil, where you get your OF?
I've had my best results mixing OF/HF 50/50%. One lg bg of each.
I add 1 cup of Dolomite lime to each mix.
The reason I add the Dolomite is because I was seeing a Mg deficiency about 1/2 way through flowering. Not because of the PH of the soil.
I start top dressing with Bat Guano at 3 to 4 weeks.
I guarantee this combo will work well for you.