Contamination problems

[Mxptrsn]

Ok I think I have a couple of questions with regard to contamination.

A couple of days ago, I sterilized my homestyle media for orchid seed flasking. I used microwave and sterilized it for 3 minutes. After that, I took them out and immediately put them in a pre-sprayed (with regular household bleach and no dilution) plastic bag and sealed them asap. The question is I used PP vessels and when I sterilized them in microwave, I just closed the cap loosely so that the heat generated would not deform the vessels. After cooling down, I then close the caps tightly. And, some of the media got contaminated. Any advice?

When it comes to orchid seed sowing, is it ok if I don't drill a hole and plaster it with micropore tape to allow gas exchange? What about baby food jars? What's the better and cheaper way?

I used organic medium formula:
2 g balanced fertilizer (NPK: 20.20.20)
7 g Agar
500 ml coconut water
500 ml distilled water
4 g activated carbon
20 g sugar
What do you think for orchid seed sowing media? Any suggestion?

Thanks very much in advance for your help.

Mxptrsn