Gooey "disk" from grey tank drain

Gkopan

During de-winterizing, after flushing the system with fresh water, this crud came out when draining the grey tank. About the diameter of the drain pipe.
Was my winterization process deficient? Thanks!

Sharon_is_SAM

Did you winterize by adding antifreeze throughout the plumbing system? That almost looks like something dried up in your tank. Was your gray tank clean before you winterized?