Its not the amendments being potent. Look cannabis needs actually very little nutes. Not that diff from us, nutrients only support bodily(or in this case plant function). The plants eat light though, that is there food. So it works like this;
1. Coco & perlite or whatever aeration used creates a near perfect environment for microbial life to bloom. Idk where this idea about it taking a long time to colonize a 3-7 gallon pot of coco with microbial life comes from, but it is incorrect. This is one of the easiest environments to grow microbial life in my friend. It is inert, it is excellent at staying moist without being 'wet', it has a very HIGH amount of oxygen & surface area. If you add microbes(even just a little bit) and food for them(in this case dry amendments) then keep the medium moist then you will have colonization in no time! Microbes grow fast.
2. No need to let it get 'hot' because it wont, however when you use it is up to you. If you think you need some time to build up microbial life then thats fine. Amend your coco & water it for a week or 2 before planting in(or plant right in as again microbes bloom fast)
3. Although microbes will occur anyway as they are literally everywhere, you are still going to want to start off with as many beneficial microbes as possible. The best way to do this is with teas/worm castings. Using kelp/castings/and compost is going to really get things going fast. From there you will want to just focus on caring for the microbes. As they bloom they will eat the dry amendments, then they will multiply, then they die. When they die they leave behind a plant ready smaller version of whatever nutrients they have been eating(You are what you eat lol). This is how microbes 'feed' plants. By feed I mean provide nutes btw.
4. As this is a coco coir/hydro grow you will almost for certain need to utilize some
calmag. Simple really.
5. Plants need 3 things. Food=light/health=nutrition/shelter=stable, friendly environment. Growers focus too much on trying to give higher & higher amounts of nutes thinking that its food, thinking that higher nutrients means more food which means more growth, but it's not the case. It's common and I had the same problem for a while before I learned a better way. Feed the microbes/ farm the microbes and in return they will give you everything you want...and not just from cannabis but any plant!
P.S All plants have a relationship with microbes. Some rely more on bacteria while some rely more on fungi. The size of the plant generally determines which. Small plants like legumes prefer a highly bacterial dominant medium while bigger plants likes trees need fungal dominance. Cannabis is kind of in the middle as it utilizes both. Both have the ability to eat & break down or 'free' up trapped nutrients, however between the 2 fungi is stronger. It eats faster therefor it frees up nutrients faster. Cannabis prefers a bacterial dominant soil in veg & a fungal dominant soil in flower. Give a bacterial dominant tea in veg to achieve a slow stream of nutes throughout the plants life, then make a fungal dominant tea for when you flip to flower.
Also as compost & earthworm casting as actually super low in nutes you can give them teas up to once a week with no problem. So the thought that there would be a lack of microbial life in coco coir is really dependent on the grower and has nothing to do with coco itself. If you can't grow microbes in coco then you will likely struggle to grow them anywhere(with the exception of 50+ gallon soil because with that volume of soil the microbial population is going to work independent/despite anything a grower might do wrong). There is also molasses lol. Don't over use it as the microbes will be eating the simple sugar before it would eat the dry amendments but if you are worried about microbial population then an occasional watering with molasses will ensure there are plenty of microbes. You just need to then let them go back to eating the dry amendments.
The lesson is that its truly is ALL ABOUT THE MICROBES. Ive seen ppl use fox farms ocean forest(a very hot highly loaded soil with in my opinion too much nutes) and have terrible results and Ive seen ppl use low amounts slow release nutes in highly microbial active soil with nothing but water and have incredible plants. In fact most ppl overuse nutrients because they think that more nutes=more or better cannabis. This isn't the case though.
Nothing can beat the nutrient cycle though in my opinion. Building soil is the way to go, but that isn't easy for everyone. For me a living soil(not coco coir)/cover crop that always keeps my mycorrhizae colonies alive/big redworm population to eat my 'green manure'(thats the cover crop when I trim it down & cover it with a half inch layer of compost) works great and as I keep this cycle going...
1. I top dress & plant cover crop
2. plant my cannabis seedling
3. bacterial compost tea early in veg
4. chop & drop the cover crop, then add dry amendments(half all purpose half bloom), then top that with about a half an inch of compost(I use Coasts of Maine lobster compost).
5. I do # 4 a week before flipping to flower to give worms/bacteria/& fungi time to eat the chop & drop & amendments and turn them into castings, then flip to flower and do a fungal dominant tea 2 or 3 weeks into flower
6. Harvest cannabis, then chop and drop again, then add all purpose or veg formula dry amendments & cover with 1/2 of compost again..
Rinse repeat. This recreates the natural order and with plenty of composting worms(red wigglers) in there you end up achieving what is known as nutrient cycling within 9 months to a year. Once that happens then you have no need for other supplements other than compost. I am currently at about 5 months into a new soil(V3 from buildasoil in 15 gal fabric pots) and it keeps getting better. This time next year I should be able to grow pretty damn well with little more than non chlorinate water/compost/mycos and my red worms.
I know this was long, but I really hope it helps.