Hi, I have a problem with my peace lilies. The leaves are turning black and dry even though I have changed the soil and ran water thru to 'rinse' the soil. Even the new growth has the same problem. I cut away the black leaves and it still is happing. I have four pots of peace lilies and they all are like this and they are not from the same group. I have two phillies that are just fine. I hope you can help. Thank you. marcia.