There are people operating DWR systems, which are using Gammurus or scud shrimp or whatever you want to call them?? in the DWR systems to clean up the dead matter and debris that settles in the troughs, now these are larger home systems with minimum 8' length troughs 4' wide, some as long as 75' in length and a 5 gpm water flow. I have visited with a man who actually said, at first he was trying to shake the gammurus from the plant roots and wash them off back into the AP water, but then he realized they were just everywhere in his system, now he just removes the plants and does not try to save any, as he said they multiply so well it is not needed. I am not sure how they would do in a small hobby system? The previous post's may be 100% correct that thy would not work well if the conditions were different than I described?