It is 'Grande' x self that I got a few years ago from Orchid Inn.
I have several that are in plastic pots - with growstone (an expanded recycled glass that is no longer available, but very large perlite would suffice), rock wool cubes, bark and oyster shell. Something like 35%:35%:25%:5-10%. Temps are lows of 52F winter with days 65-80F and lows of 58-60F summer with days 75-85F. Have grown them with consistently 62-65F at night and 80-85F during the day and they were much slower to grow. I really think they like to get down into at least the high 50s at night to grow well.
First open photo it was about 15.5cm, second is 17cm. Up to almost 18cm this morning, but the form isn't quite as nice as the petals get bigger.