After a year of letting our girls have the run of the backyard, we have decided to build a larger run for day time use so that we can replant the balance of the yard. We are giving thought to introducing a couple of bantam ducks to our five full size chickens. We like the idea of the smaller ducks and would like input on whether this is a good idea and what types of ducks would be best for an urban yard with close neighbors. We like the idea of quiet ducks. Will they get picked on by the chickens because of species/size differences? Will we have difficulty herding them into our chicken house at night to secure them? We also have the opportunity to install a duck pond as large as 4' or so in diameter and about 12" in depth. This depth will allow us to install a drain in the bottom of the pool. If I install it in the side of the pool, we could go to 15" in depth. Any recommendations as to size or depth or make? Are there such things as filtration systems for duck pools or are we faced with the necessity of draining it to clean the pool and if so, then how often?