Deficiency?

Promix has no real nutrients.. so just feeding worm castings is far from a well rounded nutrient regimen

if your using straight promix hp, then your ph is way off the mark for veg. 5.8 in veg and 6.2 6.3 in flower...

It's a magnesium deficiency or your substrate ph is not at a ideal range for absorption of magnesium would be something to look into. Ph controls with nutrition absorbs the best. 👍

Why would you foliar spray epsom salts? makes no sense. Now Epsom salts are loaded with magnesium, so what makes you think you have a Mag deficiency?? could it be your spraying a tiny amount onto the leaves instead of giving it a real dose thru the roots?? Stop foliar feeding unless your using a FULL trace element mix WITH a humic/fluvic acid booster of some kind too. Humic and Fluvic acids will carry trace elements into the plants and increase uptake from 100% to 500%. and I can go did up the study if needed to prove this, other wise foliar feeding is pointless on its own and even more so when your using Epsom salts instead of a trace element mix. If you wish to continue with Epsom salts, and I use them too so im not dissin em, then put a decent amount into some water and pour it onto the roots. That will fix the mag issue in under a week. And by decent amount Im talking a flat level tea spoon in about 5 liters of water and water with that once a week. Do that for two to 3 weeks and will know if it was a Mag issue for future grows and know how to fix it after that. Or Id dump a trace element mix onto it now Via the roots and rule out ALL deficiency's that way. Iron should be easy to fix too and also quite rare as iron is in pretty much everything. U can add ground up rust to fix it, or find iron rich red soil and use that as part of the soil mix, or make a compost from a bunch of kale, spinach ect or use blood meal. Id be leaning to Mag or Cal being the issue. So dump some Epsom salts onto the roots and u will know pretty fast if thats the issue or not.