Nice lookin' girl, and absolutely love the setupπ».
With a large soil bed like that, you might want to look into using a combination of slow release natural dry amendments for top dressing. They're a lot more forgiving, won't burn your plant and will keep the growth nice and steady. In a large bed you also want to be careful things don't go anaerobic from lack of water or too much. It's a balancing act you'll figure out over time and you want to be able to reuse that soil for several runs.
The fungus gnats 'should' mostly go away after your soil life starts to balance out. Mine were essentially gone after my first round in Earthboxes.
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