If you want to avoid the workout from lifting buckets, get a large plastic storage container or rubbish bin (my friend used a wheelie bin and another friend used a 200 litre plastic wine barrel). Put it near the tank and use a hose to fill it with water. Add the dechlorinator and let it aerate for 30 minutes or so while you drain and gravel clean the tank. Then get a small water pump and some hose and pump the new dechlorinated water into the display tank.
You can make a U out of pvc
pipe and attach it to the end of the hose that is coming off the water pump. The U goes upside down like the n and hangs over the edge of the tank so you don't need someone holding the hose and someone else turning the pump on and off.
You can attach a gravel cleaner to a garden hose and run the hose out the door onto the lawn. Then gravel clean and drain the aquarium water straight outside. No lugging buckets of water through the house.
If you have a big aquarium, you can use a 1, 1.5 or 2 litre plastic drink bottle as the gravel cleaner. Cut the bottom off the bottle and stick a garden hose in the top. Home made gravel cleaner that can drain water fast.
If you use a garden hose to fill the container, let water run through the hose for a couple of minutes before collecting any water out of it. Garden hoses have a softening agent in them to stop them kinking and breaking. The softening agent is poisonous to all birds, fish and animals so running the hose for a few minutes before using water from a hose helps to flush out the softening agent that has leached into the water. Hoses leach more softening agent in warm weather and less in cool weather.