Q.Elephant ear roots..
I have a few very large elephant ear plants about a foot from my holding tank, they are large, can they break or crack my tank? Thank you Jim B.

If they have enough room, they should not be a problem. But if they are constricted in their planting location (e.g. they don't have enough to spread) they may become a problem. I would recommend thinning them out regularly to prevent them from becoming overcrowded.
This article may help with dividing your elephant ears:
https://www.gardenguides.com/98920-separate-elephant-ears.html