In my tek it says to drill many holes in the tub, I have around 45. They are about 3/4 a cm wide. Does humidity escape from all of these holes? I'm using a few inches of hydrated perlite in my chamber. I was thinking of covering the holes with micro spore tape. To allow FAE but not to lose as much water content? Would that work? Or should I just leave it how it is.

1/4" holes - 2" apart on all 6 sides of the chamber. Don't cover the holes with tape - they will inhibit FAE which is crucial. (Plus the chamber isn't sterile at all so the tape wouldn't be helping anything anyway.)

Keep the perlite wet. Mist and fan when you can.

Roger Rbbit's Mushroom Videos

Check out part 3 of the vids - it explains the shotgun fruiting chamber.

Good luck and see you in shroom-land

depending on what your fruiting you can also give it a "hat" made from priority mail envelopes which are made of tyvek...just food for thought, your shotgun chamber should work fine with or without the micropore and one of the keys to success can be consistency, run it through unless you see severe imbalance in your environment, you can make adjustments for the next round, you may end up deciding you want some of the hole covered and some open...also consider putting a fan near your chamber it would most likely be ideal to point not directly at the chamber...i feel like im rambling but as you see there are alot of ways to make small adjustments to your environment to make it perfect

I built a shutgun chamber once..and IME yes it does loose to much of the humidity and once I switched to a fruiting chamber without any holes that I just fanned like 2-3 times a day everything improved.

Just my experience.

IME the ideal chamber depends on the media and surface to mass ratios, with large casings (lower surface to greater mass) you can fruit them just fine at lower humidity, but with cakes, (higher surface to lower mass ratio) you need higher humidity.