I was just wondering if after all the priming and cementing of pvc pipes and fittings, you guys flush the system for any length of time. This question came to mind while I was cementing my pipes and saw all of the excess cement that was going back into the plumbing. I was very mindful of the amount of cement I applied, but still I noticed it running. Does any of this excess contribute to added phosphates or silica in a new setup?....Just wondering...