I've had the same one for nearly 50 years (1968)... It gets lots of abuse and keeps on growing. They can take pretty low light conditions, and mine gets very little direct light. There is a skylight nearby, however. They'll lean towards a light source if they're not getting enough.
I don't water mine weekly.. it's usually longer, but it's in a fairly large pot. I might suggest letting it dry out a little more between watering. Stick your finger in the soil, and if it's still damp an inch down, hold off a little. If there's too much salt build up in the soil, the leaves will burn at the edges. I usually put mine outside in the summer in the shade so that the soil can be more thoroughly watered.
I've always called mine a Moana Loa plant. The name Peace Lily came later, but seems to be the accepted name now.
