Howdy organic3, I grow in DWC and clean the reservoirs by first (after removing all of the root bits and deposits) clean out the inside with soap (Dawn) and water. I then let the reservoir soak overnight filled with a 50/50 mixture of water and distilled vinegar, rinse and then another soak overnight with a 50/50 mixture of water and bleach. Finally, I rinse with plain water until all of the bleach odor is gone, or a final soak overnight with the plain water. I take apart the water pumps and clean them with water and bleach as well. The air stones and Hydrotron pebbles get tossed out, if it can not be bleached or boiled, it gets tossed.