My adductum are 21" and 18" ls, my largest anitum is 18" while the one that bloomed recently is 14". Anitum has more defined tesselation but it does show in adductum as well, leaf structure is completely different. Adductum could pass for a roths at a glance while anitum is much broader all the way to the leaf base.
I grow in a greenhouse, shaded with whitewash but bright inside, I don't have a dedicated light meter but using a phone app I see a typical minimum of about 1500 fc and the top shelf can see short peaks as high as 10,000 fc. I have my evaporative cooler set to kick on at 85° F but temps sometimes creep into the low to mid 90s. I aim for a minimum night temp of 70 during the summer and 60 in winter, though I've seen winter temps drop into the high 40s on the coldest nights. I try to keep humidity over 60%, but again it may vary some with spikes into the 90s during rain and dips during the hottest part of the day. I try to time my watering to minimize those dips.