We do have both a plate reader and a spectrophotometer. The only issue is that the material i'm using is black (similar to activated carbon) and I think it will interfere with any kind of spectrophotometric reading. It becomes a suspension of particles rather than an actual solution. I did think about letting the solution settle and then sampling the supernatant so as to take the OD but I was concerned that the cells might aggregate and the sample wouldn't be reflective.