Rob, does the potting soil you are using have moisture crystals in it? You need to add perlite or bark mulch or styrofoam beads, but not peat. Peat retains moisture like a sponge and most regular potting soils are 80% peat anyway. Those Colocasia are not happy as I see brown on the edges of all but the newest leaf. Disregard advice you find on the web that is specific to growing Colocasia outdoors when they are getting loads of sun and heat. I'm sure they'll do fine with a lighter soil and less water.
If you can more sun would be much better.
