What's so beautiful is that all along, the key to water temps is air temps. I've been poking through some other peoples thread with water temps issues. Just like I used to do, I tried addressing the water and not the cause of why it heats up - the surrounding air. If you insulate, you slow down the energy exchange between air and water. If you keep the air temps down, water temps will follow!They are gonna be packing on the growth in no time!! That is some real tough negative pressure. glad to see you just about dialed in perfectly
and this is what will make your grow cab your garage's ventilation system.
So now that gets me thinking about summer. As long as the air coming in the cab is at a reasonable temperature then everything else will follow suit.
It get's back to AC unit. I could attempt to cool the ambient temps of the garage to 68* but that's not feasible and would be a waste. But if I can create a small plenum (a chamber where the air in the chamber is kept at a constant temperature and then where ever you want to direct cooling you feed from the plenum. For example, let's say I create a box 2'x2'x2'. That's 8 cu ft of air space. If I continually draw my incoming air from the garage through the AC cooling coils into the plenum and then have all of my cabinet intakes feed off of the plenum. Then all I have to do is put the temperature probe inside the plenum and set the thermostat to say 68*.
Of course I'll have to play with it a bit. But I don't have to running headlong into it for now!