I've been installing a set of solar panels on my pool house. Been pretty careful to knock out any PVC sawdust during the process. Last night, right before I made the last connection to the inlet side of the panels, I thought it might be a good idea to open the solar valve and flush the line. That resulted in a big splash of water outside. I went ahead and hooked it up. When i got off the ladder, I noticed little bits of PVC on the ground. I'm glad I thought to flush before I tried to push that stuff through my solar panels.
