Hey everyone, I have three full grown ducks. If I have a 100 gallon trough they can swim in 24/7 that filters out some of the muck, how often would you suggest I change out the water? Also, how do I know if it's too dirty for them to drink out of? My goal is to just empty at once per week in order to save water here in Arizona. I can use the 100 gallons to water our trees. But how clean does their drinking water need to be? Can I use the pond water as their drinking water? If I give them separate water, I get TONS of mud and Mosquitos and it only actually stays cleans for one minute anyway. Thoughts?