I use the water soaking method then directly into the medium of choice.
I will scarify the seed then soak for 12 hrs and then into the soil and it seems to work well for me.
The pink scum is something that lives in the taps of water and is airborn as well.
Serratia marcescens and Aureobasidium pullulans are the main culprits, from what I can tell they are mostly harmless unless your working with fungus cultures..
Best Of luck!
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