i dont have any experience with sub's recipe.... however....
if your mix has been in the bin for a few months.... i gotta ask you... why are you putting MORE guano in it? I think you're missing the idea that matter is neither created nor destroyed. all the stuff you put in that mix when you made it
is still in that mix. it just exists in the forms of bacteria and fungal bodies. when those things die, they die IN the mix, and are consumed by more bacteria and fungi. the only way you lose nutrients from the soil is A) stuff that is soluble washes out when you water due to runoff (which runoff is unnecessary in organic growing IMO), or B) the plant takes it out of the soil to build plant tissues (the main cause for nutrients to leave the soil)
IMO, that mix would be quite hot to put a 3 week plant into, as plants that are vegging really don't require a strong mix. and likely thats why sub layers his containers when he transplants to flower. bottom layer is the full strength mix for when the plant start to bloom a few weeks after the transplant (which to me is wrong because most all plants feed in the upper root zone more so than the bottom root zone because in nature that's where the organic matter breaking down is at!), and then his upper layer is for the couple weeks in veg before flipping. but to me... this is just too much work lol. I like having one mix that works for all periods of growth, and if i need to top dress some P-K stuff for flowering, it's much simpler!
FWIW I don't use sub's mix because it contains products that are nasty to be around (bone and blood meals, guanos), and also IMO it doesn't contain enough organic matter (humus forms of EWC and compost). i'm not saying it doesn't work, because it does and we've all seen the evidence. i just prefer the cleaner more sustainable ingredients for my own reasons. not to mention... that shit be expensive!!! all those ingredients?? that's a fuck ton more that what I put into my mix. building a soil from scratch is the only way
This is the good stuff right?!
