Last week I got 4 Ancona ducks who did not have the best life before they met me. Now they have good feed lots of water and someone who cares about them. They did not have water to swim before so they are in the pool most of the day. My question is how often should I clean their pool. I just drained cleaned and refilled it this morning but it's all dirty in my opinion again. Can it be stirred up and dirty for a few days or does it need drained and cleaned daily?