Well if you read thru that documentation it does explain it all, you can read it if you want but ill basically summerize it. There is no real legal standard on how many ACH is required for a Hazmat remediation for something considered toxic like aesbestos. The basic minimum standard is 6ach but more isnt a bad thing. Now ill explain how we generally run it in a toxic situation. When doing a remediation of a large very contaminated structure for something like aesbestos (toxic airborne particulate) there are air testing machines at the chamber entrances that constantly monitor it to ensure that negative air pressure is maintained to a certain level so that there is zero possibility of any particulate escaping other than thru the filtered negative air machine. We are also required to periodically take air samples within the areas of the structure that workers are present. Most of the time my job isnt responding to emergency situations, its doing air sampling on more basic remediations to ensure safety of workers and public around that area. So for us, there is no golden rule of so many ACH that works for any and all situations, the minimum standard tho is 6 per hour and thats in a very low level of contamination. The more contaminated the area the more PPM (parts per million) will show up in air sampling and we then need to adjust to have more cfm by either adding in more neg air machines or if they are on lower settings to turn them to a higher speed. So if youre running 12 an hour, thats a good thing and you should be okay. If youre running a space thats very cramped with a very smelly plant, it means if i took an air sample the PPM would be very high and you'd need higher than that bare minimum of 6 ACH and possibly near that 12ach but id suspect not quite that high. Now if you were running a 4x4 with 2 very smelly plants you likely wouldnt even need 6 ACH as there would be less of a PPM concentration in the air. You should be more than okay with 12ach but the ultimate confirmation is going to be your own nose because im pretty sure you dont have the equipment to air sample. If i was running a cramped grow id aim for that 10-12 ach range but be running a multiple speed fan and try lowering it until i found a balance of high enough to elminate smell but as slow as possible to use less power, less noise, more longevity of carbon ect. I would guess youre 12 ach should cover even the most crowded spaces, but there are so many factors that can affect it. Even something like high humidity can lower the efficience of carbon and have that ACH reuired be higher. Your numbers sound good to me but ultimately it comes down to what air sampling says and adjust accordingly. For a grow op and smell the air sampling device is your nose. As far as the cfm ratings for fan and filter you 25-30 would be pretty bang on for a HEPA situation, with a carbon only situation you can get away with less of a difference because carbon has less air resistance than a HEPA would. Super condensed response, 12 should be more than enough but you should know if its enough just by if you can smell your plants.