From my experience PCs always grew coralline algae the quickest. I could not seem to keep it from growing in my biocubes. Tanks with Metal Halides seem to have the most trouble growing it unless you are supplementing with PC, T5s etc. I think 400watts over a 40b is way to much light and the root of your problem. Generates to much light for the ft print, excessive heat and I would think your water evaporates fast.