Obviously, this is for the salties out there...not the freshies! In the past, it has been recommended that algae screen cleanings should be done in tap water in order to kill baby copepods which tend to populate the screen, eat the algae, and cause detachment of algae from the screen. This is usually indicated by seeing a telltale circle of bare screen from detached growth. This is certainly still a possibility, but honestly I just don't see it that often anymore, and IMO it is caused by not roughing your screen up enough initially. If your screen is rough enough, the algae should anchor firmly and you may never have this problem. I personally never have had detachment issues, not once, in nearly 3 years. Some studies have shown that immersing saltwater algae in freshwater causes the individual cells to burst. Also, some scrubber users have reported that screens grow back faster when you clean/rinse in saltwater instead of tap water. That being said, people have been cleaning screens in tap water for years and most people have no issues. If you are having tank algae issues, you might have to take every possible measure to maximize filtration. Cleaning the screen with saltwater instead of tap water is just a little less convenient. The actual cleaning process should be done on a cutting board or in a sink, etc. Scrape as needed and scrub the top edge where the screen is inserted into the slot pipe. I still rinse the top edge with tap water, because you want this area really clean (and not growing back fast). Then, swish the screen vigorously in a shallow pan of tank water, dispose of that water, then fire up the scrubber again. If you use this technique, please report your results on this thread. If you encounter detachment issues, the occasional tap water cleaning might still be in order, perhaps once a month. Alternatively, you could shut off flow and dump a cup of RODI over the slot pipe, then turn flow back on right away. This should minimize algae cell bursting, but deter copepod growth. Scrub on!