steel,
i'm not sure how the hot tub pH adjuster would be.
i suggest using cider vinegar until you can get to the grow shop, or find out whether the one you have is okay.
7.8 is certainly quite high.
As for your nute, that ratio is appropriate for veg, but i would use it at a much lower concentration.
For bloom, you REALLY want to cut the N way down to less than 50% of what you had been using for veg... bloom nutes typically have an N value of only 1-3.