Thoughts opinions advice on using fox farm sledgehammer, I want to do a mini flush before regular nute feeding to prevent lockout or pH issues in soil

I use fox farm happy frog and a little ocean forest end up needing to use pH down I use citric acid works well

Soil fox farm ocean forest mixed with fox farm happy frog and perlite, I had issues with my soil pH my last 2 grows and was just trying to prevent it. I've read to flush a couple times throughout the grow to prevent it, once before going into flower and in the middle then final flush. I'm using humboldts secret golden tree and plant enzyme, watering every 2 days, that's a 3 gallon and 4 gallon pot so there not that big, been watering 700 ml per plant.

Your in soil correct.? Don't waste your money. Soil is nutrients so I'm not sure what your looking to accomplish if you haven't feed chemical nutrients to it yet. You may be looking for something like Cannazym. However, you mentioned autoflower, there's no time for that shit. Also, with a your pot bigger than your plant I'd hold off on feeding. Just focus on NOT overwatering that big pot and you'll be fine. That soil I'm guessing is either Ocean Forrest or Happy Fog and has all you need except microbes and cal/mag. Remember, more often than not, Less Is More.