The best way would be to use a shop vac. If no shop vac is available, drain as much water as you can. Bear hug the tank and move to where you can lay the tank down, elevate the button and use a garden hose to flush out the old media. To remove the bistributor tube (you called it a product tube), use a garden hose to shoot water down the center. This will loosen the media and you should be able to pull the tube straight out.