You can, and should, not cave in to long lasting commercial/marketing myths. Just use one or two drops of common dishwasher liquid soap! It does precisely what we need. No problem whatsoever.
Just enough to create a few bubbles with vigorous agitation. Using a lot is also not a big problem, you might just get too much bubbles and not enough liquid on the film surface. Again, vigorous agitation. Distiled water woud be nice, but again, in most places tap will be equivalent. Yours sure seems like it.

Best regards!