For now I am using an ordinary garden hose, with a U shaped PVC end on it, that hooks over the top of the tank. I start by hooking up the other end to a hose bib, with the PVC end laying on my deck, turning on the water briefly to clean out the hose and fill it with water. Then I carefully move the PVC end to the tank, again turn on the water briefly, to remove any air in the hose. Shut off the hose bib, and disconnect the hose, from which water immediately pours. I catch several gallons of old water in 5 gallon buckets to water my container plants on the deck, then drain the rest over the edge of the deck to the plantings below. When the water has drained down far enough, I reconnect the hose to the hose bib, and turn on the water to fill the tank. Immediately when that starts I add Prime to the tank. During the drain and refill I also wipe down the glass, pick out plant debris, etc. When the tank is nearly full I time how long it takes for the water to rise about a half inch in the tank, then use that to judge when to close the hose bib outside. After that I pick up the PVC end out of the tank, hold it high so no water spills out, and carry it back outside, drop it on the deck, and disconnect the hose from the hose bib. When I roll up the hose I keep that end high so the hose drains as I roll it up. Stick it back in the storage compartment on my deck and I'm done.
In the winter I will probably switch to 25% water changes twice a week, so the colder water won't harm the fish.