Ok first I admit that mushroom compost and rice hulls are foreign to me, but I think I understand them. So here goes.
EWC and Mushroom compost are both organic matter, so 25% of the mix. I would go 2 parts EWC and 1 part 'shroom dirt to make the 25%.
Used soil, I like 50% of the mix. You built those humates last grow, may as well use them again, not to mention the myco spores in it.
Coco coir I like to add 10% of the mix.
Biochar I would use 5%.
So now you are at 90%.
Rice hulls, for a practical comparison, are a combination of perlite and coco in function that slowly degrades into carbon and organic matter but it is slightly less carbony than coco and slightly less areationy than perlite. It is however diversity from both and that has immense value. So 10% rice hulls.
Toss in your ammendments, mix the daylights out of it, then add in perlite. Perlite is inert. Don't count it's volume in your mix, you add it after the mix is created. So 10 gallons of mix turns into 13 or 14 after perlite is added, then cook it.
I like 30-35% perlite overall. Used soil brings perlite in so I use a half gallon of perlite for every gallon of coco added, and a half gallon of perlite for every gallon of EWC added, and that gets it close. Then after a good mixing I add a bit more by eye to get it where I like it.
I would use all of those ammendments you listed except epsom salts. I have only experienced grief with them. Others swear by them but I cannot for how I mix my soils.
What you haven't mentioned is calcium.
You should have dolomite to properly set the CEC, gypsum for the sulfur and ph stability, and oyster shell flour for slow release.
I like 1.5 cups/10 gallons of soil of dolomite before perlite is added, .5 cups gypsum before perliting, and .5 cups oyster flour before perliting.
Here is my favorite soil recipe before perliting. It's a strong mix because Cropking Durban Poison seeds can handle it. You can lower everything by 25% if you have a light feeder, or cut it with more used soil. I mix a tub of high strength and cut it down with used soil if needed. It simplifies life.
20 gals recycled soil
2 gals coco
3 cups prilled dolomite
1 cup blood meal
.5 cup bat guano
.5 cup glacial rock dust or .5c rock phos
3 cups feather meal
3 cups bone meal
1.5 cups greensand
.3 cups SRP
2 cups organic basmati
1 cup gypsum
3 cups kelp meal
2 cups alfalfa meal
1 cup oyster shell flour
Add spikes and you can grow from seed to harvest with water and fish ferts and EWC. It is designed for zero ppm RO water. Spikes are just topdressing in a hole.
It's a high brix recipe that from what I have discussed with Doc's followers, gets higher brix on the refractometer than his foliar system, which is good, as that was my goal.
Brix consistently over 20, almost always 21 or 22, and I hit 26 once. Over 20 and brix becomes strain dependant. Some strains photosynthesize better than others, it's a DNA thing that can't be overcome.
I hate bugs, they bug me.
I also use 1tea application per grow for sure, at about 3-4 werks from sprout, and quite often a 2nd tea at flip, but not always. It depends on vigor and brix at the time of flip.
So theres some good stuff to help you figure a mix. Talk it out in here if you like, and everyone join in or stop the conversation please if you get lost. Your mix determines your outcome so this is where a good or mediocre or bad experience is created.
This is where you should speak up if you are a lurker and still unsure. We can talk about this for weeks if needed, I don't mind at all. Get the mix right and the rest gets easy.
013 spoke up.
.
.
