Hello Chris,
I grow this plant outside and it gets morning sun and gets huge. I have the plant on a drip irrigation. I water it every other day and also fertilize. My plants are in well draining soil with lots of mulch. From the picture it does not look like the black stem form but the red stem form. It may be the picture or my eyes. These are Colocasias. They are called Colocasia esculenta "Red Stem". I have attache a link to Agristarts with growing information.
AGRI-STARTS, INC.: Colocasia esculenta 'Red Stem'
One of your pictures looks like the red stem form and the other looks like the black stem form called Colocasia fontenesii "Black Stem" form. The growing information for the black stem form is below.
AGRI-STARTS, INC.: Colocasia fontenesii 'Black Stem'
I hope this helps.