I decided I wanted to change some of my plumbing around and so I began hacking at the pipes. I am amazed at the build up of gunck over the last five years. It got me wondering if this should be done routinely every few years. I will certainly get improved flow rates and not having my water passing through dirty pipes will certainly be good from a nutrient stand point. So does anyone already do this? If so how often? With multiple pumps hard plumbed in the only option I would have for cleaning them is to switch them out. Cost a fair bit with all the unions and valves so is it worth it?