Orange, sulpher smelling effluent

[Jboy]

Hi there, I have a canreef Ca reactor which has been working fine. My bubble count is about 8/min, and my drip rate is about 25 min. The PH is of the effluent is 6.8. Like most people, I collect the effluent in a cup which overflows into the sump.

A few weeks ago, the effluent cup became all orange, and the effluent started to smell like sulpher. Nothing seems terribly wrong, but I am now getting a thin orange ppt "film" on the top of the effluent in the cup, and the smell is getting a bit stronger.

Any ideas?

Thanks
Jason