1 – I would suggest that you flush out the entire system 2 or 3 times

2 – Disconnect the main 1 ½” hose from the rear of the head and from the rear of the holding tank. To make it easy, carefully make a cut along the hose and pry off. Drill a small hole in the end of the hose under the sink and attach a messenger line. Pull the hose forward into the main cabin. Remove the hoses on the outlet side of the tank. In order to reach the hose clamps on the waste pump out deck fitting, you must remove the corner piece over the hanging locker (to get this out, remove the teak trim along the starboard side of the cabin). You will have to drill a hole in the headliner to reach the hose clamps

3 – Remove the plywood top over the