HI SpideyGirl hope this helps, Light requirements for Philodendrons.
Philodendrons will tolerate some shade but prefer strong light. Light requirements for indoors are four to eight hours of filtered light. Do no place the plant in a window where it will receive direct sunlight through the glass.
As for the Water and Soil
Philodendrons prefer slightly moist soil. They like misting of foliage well. In containers philodendron selloum prefers a good organic, loose, and well-drained soil like premium potting soil mix.
Fertilizing Philodendrons
Feed lightly and frequently for good growth and color with a 20-20-20 or similar tropical house plant fertilizer for indoors,I do not think its the iron in the water,I use well water on all of my plants and they do very well.
You might try moving it back to the display window for a few days and see if that helps,they don't like to tightly packed soil,try this and see how it works for you,and good luck,also here is a link to help you troubleshoot your house plants.
http://www.thegardenhelper.com/troubleshooting.htmlyour friend in gardening.Mike57