Originally Posted by Smitty
That's what I used. I didn't use a separate vent/gravity fill. Rather, I put on a radiator-type hose that serves a dual purpose. Vents fine, and can use it as a gravity fill if I absolutely have to (more often I use it to pour in a bleach solution). Beware, if the hose has a dip where water can collect...it can create havoc when filling. Basically you're putting water in, air can't escape, tank expands, and eventually has to burp (very, very messy). So just be very careful.
You can buy an adapter that will fit on the end of a plain hose, faucet, etc. and then connect a water hose to that. Handy, because a lot of water fill areas will have just a plain hose with the end cut off (so you'd have to use the gravity fill). With the adapter you just fit it over the hose, then connect your regular hose, and connect that to your water inlet. I've only run into one water hose that was too small for the adapter to work (was much smaller than my pinky...dunno what they were thinking).