Interesting idea with the Winogradsky column, never heard of that! I will definitely give that a try. But yes I saw on Amazon they have these guys and you just fill them up into the petri dishes and then you're good. I was going to go with a powder but I specifically saw instructions about the use of an autoclave (or pressure cooker like you mentioned) but my parents don't have one :/. Just looked though and they're pretty cheap for a little 6 qt one, and I think that would be more than enough. Will pick up some distilled h2o too! Thank you!