I have a nice sturdy plastic kiddy pool about 4' X 6' for 5 Khaki Campbell ducks & 2 Embden geese. How often & how well does it need to be cleaned? Right now I drain it (with hoses siphoning the water out to nearby garden beds) every other night. In the morning I *try* to scrub out all the brown residue & the green algae from the bottom & sides & give it a good rinse with the hose before refilling. Over time, however, there seems to be a build-up of algae on the sides & dark brown stuff imbedded in the bottom (the bottom is textured for a non-slip surface for children). Just how clean do waterfowl need their pools to be? Water-foul is more like it!