We also have 1 drake and 2 ladies. The biggest thing is space. We built a 460 sqft covered pen intending to have 6 total ducks.
It includes an 80sqft pool. We built on a slight slope so the pool has a bottom drain that we can open to completely empty and clean, it flows downhill to the garden. I do that about weekly.
We put them in a 25sqft hutch at night. We use straw as bedding, and use one of those extended trash grabber things to pick out poop roughly every day. 
Every month or two we dump the straw from the hutch on to the ground. Our soil is clay, so hard to grow grass for them. We made the mistake (my opinion) of using pea gravel around the pool. At first it was fine, but it got kicked around on to the clay, and at that point just became painful to walk on. So the straw cushions the ground. Once in a while we remove all the straw for use as mulch/compost.