I have a colleague at work who has sent me a friend request on Facebook, but I don't feel we're close enough for them to be seeing my personal posts, I'm not sure how they feel though, they could think we are.
I personally don't think Facebook is suitable for work relationships but much rather LinkedIn. I'm more than happy to connect with them on that, as we already are. I also just don't want to decline the friend request without an explanation.
How to politely (and professionally) decline the friend request without causing any animosity between us?
Note: They'll know if I have declined the request as we use the Facebook SDK in our job (mobile app development) which requires me to use Facebook throughout the day, so I would much rather explain than just decline. Also, it's a relatively small office so we speak on a daily basis.