Are you in FFOF soil? Have you really used that much nutes or any in the first 4 weeks?
This is only my opinion but first off I would not use Sledgehammer. Second, there is no need to flush in between veg and flower unless you have been adding in nutes from early on.
I only flush the last week before harvest because I use FFOF and transplant twice in veg, I don't even begin nutes until a week or so in flower so I have no reason to flush at the 12/12 mark. At final week I pour in just plain water, about 2x the gallons of the pot size, then next water I pour in the same amount of water as the size of the pots, the last water is usually a gallon less then the pot size, then when that dried out I harvest.
I use the ENTIRE fox farm nute lineup in FFOF soil but I do not use Sledgehammer because i see no point to being there is no salt build-up in my situation.
Being you are staying in veg I would not flush, but then again I'm not taking clones as of yet so hopefully someone who knows more on that chimes in.