I started the second experiment with making bulk substrate from horse manure pellets. My straw experiment failed and many people advised to use coir instead, so I tried it.

The 600 g brick is said to be dissolved in 10 litres of water. Hence I measured 60 grams and dissolved in one liter:





Now it's too watery so I strained the excess water and measured 50 g of horse manure pellets (these should be worth 500 g of real horse manure). It didn't fully dissolve so I added hot water (200 ml in total):





Now I mixed everything along with 50 g peat moss (let's make it look more like soil) and a spoonful of gypsum:



The excess water has been strained in a collander (I had to squeeze it by hand):



Now it looks like real substrate. The better and more straightforward course of action would be to measure correct amount of water, dissolve the manure pellets in it and then mix everything.

Anyway, I loaded the substate into 1 liter jar and paseurized at 60-70 C for one hour:



Finally, the substrate has been cooled and layered in a monotub (4 layers of substrate with 3 layers of grain):



I left 3 holes (8 mm wide) with a micropore tape for air exchange:



These mini-monotubs has been placed in a larger monotub and left to colonize along with my straw mini-monotubs:





This probably won't work since the grain smelled little bit like rotten cheese and stopped colonizing two weeks ago (probably from too little AE). I spawned it anyway just to see what happens.

It would be nice to have some knowledge on how much of each ingredient to use (ideally by weight), but all the recipes are for real horse manure, not for pellets. One source said the pellets are 10x stronger than dried horse manure by weight, so this is the only information I can work with.

If you have any ideas or suggestions, please let me know...

From what i can see this looks good I can't help with the HPoo Peletts as I am not familiar with using them, but I think that your myc spawn will surprise you and colonize the bulk sub.

If anything it looks like a very high spawn to sub ratio you can probably get away with using a bit more bulk substrate your next go around but good luck and i cant wait to see those bad boys fruit

I will keep an eye out for updates and help where I can

Thanks. Sure I will update the thread with more photos in the next weeks.

This was just a little experiment to get hold of coir, I hope the recipe will solidify over time.

Maybe I will continue doing these mini-monotubs with varying parameters to see what works best.

Great idea I find a simple Coir/Verm + gypsum is almost foolproof for substrate 50% Coir 50% Verm + 1 small handfull of gypsum

This is also great substrate working for many people. I would like to include manure for nutrition (I grow cubensis and they love poo) but since the pellets almost completely dissolve, it would be easy to just pour the brown water in the coir/verm mix.

That does not look like a montotub grow. The substrate/grains should be in the monotub, not in separate Tupperware containers. Doesn't seem like you will get the right airflow the way you have it now.

I mix the grains into the substrate, never tried layers. I guess that should be fine.

What was the substrate to spwan ratio? Anything above 50% is more difficult to get to work (longer colonization time, more chances of contamination, etc).

Did you do a field capapciy test on the substrate to check for proper moisture levels? You started with very wet substrate, you may still have too much water.

I worry your airflow is wrong, that your water content is too high, and that your substrate/spawn ratio is high. Any one if these things will result in failure. You also mentioned the spawn quality is questionable.

If I were you I would cover the monotub holes loosely with polyfill and dump the small tupperware (what you call small monotub) contents into the cleaned large monototub, and if the field capacity test fails, add more dry ingredients until you pass. Gypsum also helps cover up sins from too much moisture as it can soak up some excess. Then add colonized grain until you are at least at 50% ratio if you are not there already. Or if the original grain is really funky just start over.

Field capacity test video here. Essentially you want a only one or two drops to come out when you squeeze the wet substrate hard.

I have a tub going. Can post pictures when I get home if you want. Cheers and good luck. Monotub grows can be very rewarding, hang in there.

Ok, here is a picture of a monotub finishing colonization. Will fruit on its own in a few days I bet. Colonized grains where mixed in to the pasteurized substrate 10 days ago. Can give more details if interested.