Also want to throw in that a lot of folks use mycorhizae in organic soil grows. When they break down the organic matter they put out food for the plant in a pretty acidity form. As long as your microbes are in abundance and healthy you should be just fine with low ph runoff. If you are that concerned with getting it up into the range you're looking for then you should do a slurry test for ph in the soil. Much more accurate way to see what is going on.
Which Black Gold soil are you using? I have never used it, & don't feel like looking them all up. It may have
Mykos already in it, which if you read Danky's post I quoted above, could explain what is happening. Or perhaps you added
Mykos into the soil yourself (I always do) When you made the soil recipe did you add lime? In other words, what was your soil PH before?
As mentioned, (I'm just tacking on another vote) do a slurry test, much easier to see what is going on in my opinion. You are using calculations to try to figure something out, when there is already a simple, direct, test you can do to know your soil PH.
I can also vouch for the
Nectar for the Gods Olympus Up if you are soil. Also mentioned, the
Herculean Harvest. All the soil grows I have done have been with
Nectar for the Gods, so I'm pretty familiar with them. If you find the right store, they were giving away free boxes of the intermediate nutrients. I think I got 8 bottles with the
Olympus Up & Khaos Bloom added. The boxes are sent to the retailer with a large sticker that says "Free samples only, not for resale," or something to that effect. Of course, if you find a store that still has that, you have to spend a little money for them to want to give you a large box of nutes.
But see what your soil PH actually is, & we can go from there. As mentioned, your water PH is not as important in soil. My water is 6.4, I would say the average ph of my soil was 5.8, but my runoff would also be right around 5.8. Which, I guess, is not happening for you.
As a side note, I'm willing to bet you are doing Autos because someone told you to start out easy. In my opinion, there is nothing easier about Autos except for not having to change the light cycle if you so desire. But how hard is it to put a light on a timer? I think I've run 10 autos total, just for the experience, & I didn't find anything about them that made me prefer them over photos. In fact, the only one I grew that was actually a good product was an Ak49. All the others were nothing like their photo cousins. Obviously, I haven't tried them all, but the ones I have tried, I was not impressed with.
So, some people say to start out with Autos, because it's easier. I think they are actually harder, because you don't have veg time, or control of when it flips. If you were doing photos, you can easily control exactly how you want your plant to grow. Top it, lst it, & I like to do a variation of a scrog. Once you have your plants where you want them, with tops nice & even, good spacing etc, you yield far more, & in my opinion better bud. A real example, the auto White Widow & the photo WW I grew, from the same company were nothing alike, in any aspect. The auto yielded 1.5 oz, the photo yielded 10 oz. Taste, high, yield, smell...just not in the same league.
So I would do photos on your next run. If you prefer the autos, I'll eat my hat. If you want suggestions on easy photos to run (not fragile or finicky) you can message me, or start a thread in the appropriate section. Some strains are not the easiest for a beginner, but there are SO MANY others strains that will take almost anything you can throw at it.
Do that slurry test! I'm interested in what is going on here...
