When you leave the valve open there is no water sitting in the bottom of the tank....and then you start building a poop mountain. The outlet is on the edge of the tank and there is no way it will wash over to that hole. You will end up with toxic concrete mix in the bottom of your tank. Best way is top off tank once a week then pull the lever. Most will wash out then, then back flush. After finished close up valve, add some chem and water...repeat weekly.
The more liquid there is in the tank the better.
2015 338RETS Eagle Premier gloss sides., king.
2012 Ram 3500, crew cab 4x4 duelly Deleted
16k miles, 530HP, 1000 +torque.