I've built a few auto setups over the years.
They started out complicated and got simpler over time even as my yields continued to increase.
One of the things I quit bothering with was misting. One of the things I did more of was fresh air exchange.
Dunking and maintaining the proper humidity with maximum fresh air exchange are where it's at IMO. This also saves you all the trouble and expense of building a misting system and you can use that time and budget to make something that makes dunking easier instead (if you're going big and need to do a LOT of dunking and draining, that is).
One thing I found that helps a lot for draining smaller trays (roughly litter box size) is to use pieces of square plastic grid (also called diffuser) commonly used for fluorescent lights in offices:
I cut pieces of it to fit inside my trays and use them to hold the substrates in the tray as I tip it over to drain the dunk water so they don't break into chunks, fall out, and make a contaminant-prone mess. If I'm being extra careful (any suspected contamination present at all) I use a separate grid for each tray to prevent cross-contamination. I dunk the grids in a solution of iodophor just before I use them. BTF Iodophor is the most commonly used brand (get it at homebrew supply places or online).
The easier dunking and draining is the more we'll do it, and the more we do it the better our yields will be, all other things being equal. So do it between EVERY flush, no slacking! And maybe before the first flush, too depending on substrate moisture content.
The real trick to this automation game is figuring out how to maximize the fresh air exchange (constant would be ideal) while also maintaining the ideal rH (assuming adequate substrate moisture).
Having (presumably) electric circulation fans in a very high humidity environment is challenging, too. You'd probably want something sold for marine use, like a bilge fan or something rated for water exposure and preferably low-voltage DC powered. PC cooling fans might work for a while but aren't rated for running in such a high rH, so if you use those please report back eventually on how well/long they worked as I'm sure I'm not the only person who would be curious to know.
Edited by TVCasualty, 28 July 2021 - 05:57 PM.