@Mark Parker coir has a great property where if its quality coir it doesn't need additional aeration. Coir fibers are actually long tubes that will retain more water than peat, but also hold more air than peat as well. You could add compost, but that might throw off coir's aeration properties as it is often hydrophilic once saturated. Just coir works well. Regarding nutrients, I use a fertilizer injector to fertigate Agrothrive GP 3-3-2. I'd feed once every 3 days. There are studies out there showing that water soluable organic fertilizer is taken up faster than dry organic fertilizers that have to be digested by microbes before plant available. I try adding nutrients laden water at time of hydration, but if you get the water too hot, it'll kill a lot of the beneficial microbes in the solution. Also, your nutrients have a greater likelihood of off gassing before you have a living plant root there to take it up. That's why I would wait 3 days after germ to feed the first time. If youre interested in agrothrive, I did set up an affiliate code with them code NBarS should give you 5 or 10% off. I landed on them after trying lots of organic fertilizers to balance strength, solubility, and smell. Cause some are rank, and its worse in indoor grows. Oh, and I'm now longer just growing with organic practices, I am USDA Certified. So if you ever have any questions about the process feel free to hit me up.

@Mark Parker oh, and updated info... I no longer use coir. I use Coast of Maine Sprout Island. I consistently get 3 to 4 ounces more on brassicas which is 80% of what I grow, using sprout island over coir + nutrients. It is about .50 per tray more expensive, but i am grossing $6 to $8 per tray more. Im fine with that trade off. It also is a more streamlined process to get trays filled with no rehydration step.

@Josh Beard the professional greenhouse growers you see are using rolling nursery tables. They are usually made of galvanized steel. https://www.instagram.com/reel/DGmJp1DtkEy/?igsh=cnRqcXRvMGk3NXpi

@Josh Beard the issue with this line of thinking is its only considering the immediate cost, rather than longer term costs and Non-monetary costs. Getting wooden. Racks that aren't sealed will lead to mold and rotting, as well as a porous surface has a greater likelihood of harboring pathogens or other diseases that can negatively impact your grows. That's why you see people using metal rack systems no matter the location of the grow. I hate to say it, but if youre growing micros for commercial sales, the cost of a wire rack is negligible, as you make it up with selling 7 trays worth. If you keep this bootstrapping mindset, you will always find it difficult to scale.

@LaReina Olson i agree with this. The only things I code are my salad mix and spicy mix, as they are very similar and mixing them up the wrong way is no Bueno. And when slinging 40 trays in 4 hours at the farmers market, I need a quick reference. Essentially I have white and black bottom and insert trays. If my temray combo is black and white I know it's spicy. If it's black and black it's salad mix.

I always seeded at 1g, per Robert Meredith. It's a long grow, like 45 days to harvest. But then it can grow for months. Remember to feed it! And as @LaReina Olson said, humidity dome until germinated, mist daily.

I'll say this much... I have tested promix that you can get at the big box stores like this. But I always had major mold issues on just about every crop. No clue why it's an issue with these and not the nursery compressed bales like HP or MP. Likely because the big box bales are meant as potting mixes and have too much fertilizer in them for germination purposes. Hope it works for you!