Hello all, Help please. I am currently refitting a tank which has only had plants in it for some time. Although it was not heated the plants were doing very well. I then tranfered them to a smaller tank to allow access to the larger. on returning from a weeks holiday I found the plants to be heavily coated with a brownish deposit the only differenc to the previous setup was that the lights were closer to the plants. Is this what has caused the problem?