A siphon hose that us fishkeepers use for fish tanks could be helpful if you dont want to flip over the tub but ducks are masters at getting their water dirty
That’s a loaded question with ducks lol It also depends on what you are using as their water source. I currently have a lined 7x14’ pond so I use enzyme tabs for in between when I use a sump pump. I am adding a bio and uv filtration system next. I used to have stock tanks that my husband rigged some pvc pipe, on/off valve and a drainage hose. It was nice because I could put the drainage hose in my tank that I use to water the garden so the water wasn’t wasted. He also put a float valve the stock so that it automatically refilled once the water got below a certain point.
This is my first year with ducks/geese and let me tell you it has been trial and error from day one.
I have 3 kiddie pools and drain them daily. I have a Milwaukee cordless water pump and pump it all away from the area, rinse and refill. I also can give them fresh water every 5 minutes and they will choose a mud puddle EVERY SINGLE TIME. I have often thought of getting a stock tank but draining over 300 gallons of water a day I would need to figure out a cleaning system. Fish tank vacuums or a pool cleaner/vacuums seem to work for some people.