Hello all, I am new to this forum. I am designing a small commercial oyster mushroom farm. I plan to post my comprehensive design when it is complete. My initial fruiting chamber will be 10ftx12ft by 8 feet high. I have read a number of books and read thousands of forum posts, but cannot find information on reducing spore loads in fruiting chambers using misters. In Paul Stamets 3rd edition of Growing Gourmet and Medicinal Mushrooms, pg 486, he suggests using misters in the recirculating ducts to wash the spores out of the air and place the duct over a drain. However, there is not much detail in his book and as we know, the devil is in the detail. Therefore, I am proposing the following system and would appreciate any feedback, both positive and negative, and alternatives. 1. Horizontal 4-inch PVC pipe (i.e., air duct) ring at the intersection of the wall and the ceiling around the entire room. 2. Continuously running recirculating fan: Vortex VTX400 Vortex 172 CFM Powerfan, 4", with speed controller to obtain desired air exchange rate. Please note I will have a separate system for fresh air input. 3. In one corner, I will have a vertical 4-inch PVC air duct connected to the horizontal duct at the ceiling. I will install a mister towards the top to flush the spores with the water/mist. This duct will go through the floor (or wall) and exit the building, thus acting as a drain for the water/spore mixture. On advantage to this system is the misting duct/drain will operate continuously and thus will always be under positive pressure preventing flies and other insects from entering the drain. This will also reduce the spore load, which will increase the life of the circulation fan as well as the window air conditioner fan and filter. One last question, how many times per hour should the fruiting chamber air be recirculated? Please note that this is independent of the amount of fresh air needed to maintain the appropriate CO2 level. Thank you in advance for your input and suggestions.