Need advice, not so slow leak in sump

[gregzz4]

Glad to hear you found a minor issue

To answer your question about the silicone, I'd let it sit for an absolute minimum of 24 hours with a fan blowing on it to help off-gas the VOCs and speed curing
Better would be a few days
When uncured silicone gets wet it turns to muck and you're done

So, if it were me, I'd buy a new bulkhead and install it without any silicone

Good luck my dear