It should be. I believe one is a skimmer and one is a reactor. Can you call your friend? What's the temp? Do you know who to test parameters?
I'd like to help and hopefully more members will chime in but it's kind of hard if your babysitting a friends tank and your not sure what's what... Or what should be on or off. Not your fault at all. Just saying...
"When creating an aqua scape, strive for the beauty of imperfection, as its art and there is no wrong or right, it's left open for interpretation" James Findley