anthuium leaves large dark spots underneath

[Kdot]

Anthuium has large dark spots on underside if leaves, can't even see them from above. What is going on with it? Does it need a remedy?

Thanks!

 

[DirtMechanic]

Do you give it 6 ice cubes of water per week? Those are lower leaves and could just be going by as they do not last forever, but that one spot on the right looks odd.

 

[Kdot]

I just read about ice cubes, never heard of that. I occasionally pull yellow leaves off the bottom, not sure if overwatering would cause brown spots too. Thanks for the tip!