Fan for about 15 minutes at a time. Or a quick 5 minute fan a little more often.
After every time you fan and air out you want to gently mist from a distance as fine mist as possible from your spray bottle. Also, make sure than you spray the sides of your growing chamber and the inside of the lid very lightly, to help bring humidity back up.
At this point contaminants are less of an issue. The mycelium needs to be stimulated with fresh air and light to begin the pinning process. We will talk about light on the next page.
A good tool for automated air exchange is by using an aquarium air pump to pump fresh air into your chamber. You want to keep the pump outside of your chamber and run the tubing into your chamber so that you're pumping fresh air and not stale air.
Drill a small hole on the side of your chamber where you are going to bring your tubing in. Use a glue gun or caulk to seal the circle and keep the tubing in place.
If you want extra cleanliness you can do this: Grab an old shoe box and cut 2 holes on opposite sides of each other. In one hole, you will run the tubing through to go to your chamber. On the other hole you will run the power cord through to either a wall outlet or an extention cord. You will lay your air pump inside the box. Keeping in mind that this box is going to be closed at all times, we want to avoid the air pump from overheating. So if your air pump allows you, remove the bottom plastic cover on the bottom of the pump. Most air pumps will let you take the cover off, but some won't.
Place your air pump bottoms up and close the shoe box. Tape it closed for extra firmness.
Now, what you want to do is cover all the holes with polyfill. Polyfill can be found for about a dollar at any discount retail store (like Wal-Mart). It is what most stuffed animals and some pillows are filled with. This is a good and cheap air filtration technique. This way your babies will be automatically provided with fresh air 24/7.
tubing running into a cooler style chamber
If you do plan on using the "shoe box teck," your cakes and your primordia will love the 24/7 air exchange, but this will not suffice. You still have to air out the growing chamber at least once a day.