We address the nitrogen issue by phasing out the MagNifiCal. if you notice in our calculator (
www.remonutrients.com/calculator), we recommend discontinuing the product after week 5. You're right about the effects of nitrogen overfeeding but after diluting, 3% is not really that unreasonable. Nitrogen can't be totally removed or fan leaves start dying as soon as you flip to flower.
Velokelp has kelp derived enzymes. We use cold pressed liquid kelp extract for this product so some of the bennies are available due to no heat being added during extraction. As for third party products, we've used zyme and great white during veg to break down left over roots in the medium after reconditioning our coco for re-use.
Hope that helps,
Joel