How do you control the seed of the steam effect so there is more steam when the effect begins?
There is no direct control over the seed parameter yet. (This is something we will add in a future update.) But you can effectively get a different random seed if you delete and reapply an emitter a second time. (Every time a new emitter is applied it gets a different random seed.)
If you haven’t yet updated to Continuum 12.0.1 please do so, as it offers many more controls over particle properties that should help in fine tuning the look you’re after.