Well, I missed my very narrow window for top crop it seems as the krausen disappeared during today (open ferment for first bit) and it's down to 1.011 in just 30hrs. Will see if it gets to the calculated FG of 1.006 but seems close to flat - maybe a couple more points over the next week. The pitch calculator said I actually need two rounds of starter given it was four months old.
I'll try saving and washing some sludge for practice and maybe another beer brew opportunity comes up in the next month. I'd definitely test it before pitching. To me, yeast is the unknown beast [do I need a 400x microscope?!].
I forgot to add Irish Moss (or whirlfloc) - I have isinglass and wonder if I can add this when I put it in the cask?