Preparing for my first water change in my RDWC setup (in my sig). Plants just entered their 2nd week of Veg this past weekend (now on day 22 since popped seeds entered RW cube into basket). Using AN nutes since 1st week of Veg, the inside of the res and the (6) 5-gal buckets have a brown film on the sides of the bucket under the water line. I want to be able to clean this film out while I get rid of the soup and then add new RO water and new nutes. How do I change the water and wipe out the brown film from the soup without disrupting the plants or putting them into shock of some kind? This is my first hydro grow and it's going well so far, don't want to go the other direction.... More specifically...what do I do when I lift out the nets that have the roots protruding 12" or more into the buckets? I do have extra 5 gallon (clean) buckets with an identical RDWC system I don't have setup yet....should I just transplant them into those buckets w/no water and have the roots suspend in air while I clean out the entire 7 bucket system?