My View did not have a gravity fill. I would hold the hose up and pour chlorine down the hose, then attach it and turn the water on.
The gravity fill is probably behind a locked door as mentioned by others. DO NOT just shove the hose in it, it blocks the air trying to escape, make or buy an adapter.
Hope the image is not too big. anyhow, I made mine from hose and fittings I bought, it needs to allow the air to escape easily when filling. My filler actually goes uphill then down to the tank so I made a long one that goes all the way to the tank.
Charles