I have been looking through the threads trying to find some way to keep the duck pool clean. Everywhere saying it can't be done, that ducks are just messy and just have to deal with it (that was the gist of it at least). So, let's start at the beginning: First, we started with the basics of just a pool (a small kiddy pool, that they quickly grew out of) and having to dump and fill it daily, sometimes lucky to get two days. Since they grew out of the other pool, we got a bigger kiddy pool (the one with the slide). So, to make water change process easier, we installed a drain so we wouldn't have to flip the pool. But still left with a 1-2 day water change. Then it hit me: how does nature clean surface water. Well it's quite simple really: plants, movement, and bacteria. So I found a filter design that provides this: the biofilter. There are many designs of biofilters out there, but I went with a modified skippy design. The only real modifications I made was the filter media and the spout leading back to the pool. The total for this filter was around $175 (plus another $180 for the pump since we didn't have one yet) and about 2 hours of labor. But the real bonus is that if cared for properly, we shouldn't ever have to drain or clean the filter or anything. Fully self-sustainable. This is a quick shot of the temporary setup (we plan to increase the pond size substantially). As you can see the pvc pipe poring (waterfall kind of deal) into the pool. The drain is in the bottom and goes underground, outside the fence to the pump. This is the top view of the filter tank (the treated 2x4s are not necessary, it was an addition I made to keep the pvc pipe straight up and down when the tank wasn't perfectly level..now it is level, could take them out, just don't feel like it.) You want the filter tank open to allow sunlight in, this helps clean the water as well as it kills some organisms and bad bacteria. It also allows for plants to be added to eat things up such as the nitrogen released by the beneficial bacteria. For filter media, it is imperative to choose plastic material, really thin and fibery. This is because that is where the bacteria will grow and live. It also helps trap the particles in the water. For our filter media, we chose a couple different materials (all loosely thrown in): - Bird netting - scrubber pads (kind of like scotch bright pads, but looser fibers, got them at a dollor store). - and some actual filter media pieces (scrap from a pet & aquarium store) (The actual skippy filter uses floor scrubbing pads cut up into rectangles and loosely thrown in. We chose aquatic hyacinths for our plants, started with 3 and they have multiplied to 9 in just a couple weeks. So they are feasting quite well. When we build the actual pond, we will add more plants like reeds, water lilies, etc. we may also add fish and other animals to the pond. It has been about 3 weeks since we built and installed the filter. The first week we did have to drain and refill the system as we didn't have the beneficial bacteria in yet. But once we added the bacteria, the water cleaned up nicely and we haven't had to do anything except top off the water (we have well water, so no worries of chlorine killing the bacteria or anything else). The only worries we have is come winter as we get bad winters, down well into the negatives (New England). So freezing is an issue. The water movement will help to keep things unfrozen, but only so much. Thought about adding a pond heater and a heater to the filter tank to keep the water above 40 degrees, but I don't know if that would be enough to counter the negative 20s or worse we get sometimes. Now for those of you that live connected to a water grid (my condolences and sympathies)... This system may not work for you. This is because the chlorine in the water will kill the beneficial bacteria. The bacteria is key to the function of this system, without it no clean water. HOWEVER, if you get it up and running, topping off shouldn't do much of anything. The colony can also be repopulated if need be, but that's extra work and extra water...kind of defeats the purpose. I will add a couple more pictures tomorrow to show how clean the water is. The entire current setup our ducks have is temporary, it will be improved greatly once some funds are available to do so. (New raised duck house with deck and feeding area is already designed, working on how to roof the entire 48'x48' area and pond design is in the works).