We clean each Quad water system once a minth. They are on a maintenance rotation so that each quad is cleaned monthly. Since we have switched to the RBP liquid gold we no longer have the build up in the pans or in the resivoir. To do a good cleaning the best way is to pull the water box out , at that point you can pull the pan to clean it.
Once a month is about the same we clean them. There's no easy method that I know of, just take them apart and get everything cleaned up good. Marine grease is used on the outside of the bearing's to help them to last longer and to keep the fungus down a little clorox in the tank helps.