We are planning on using a Tractor Supply round water stock tank for our duck pond. It is 8' diameter and I think that's 300 gallons. * I know I could dig one for cheaper but my health would make it difficult.
Since it will be 300 gallons I would like to use some sort of filtration so I do not need to do as many water changes. Any suggestions on what type of filtration for this size volume of water? I can do either electric or solar. Which ever will do the best job. We will try to use some sort of ground cover around the pond so that they do not track as much grass and dirt as they are now doing with their kiddie pool.
Also, is an 8' diameter 2' high tank big enough to maybe add some fish or plants? If yes what plants would they NOT eat?
How many ducks are you going to have using the pond? I think that will probably be a big determiner in what type of filter you use. I know when we tried to have a filter on our duck pond (with 8 ducks and probably 500-600 gallons), that the filter kept clogging. We used a really big filter (I'll ask my husband what it was, as he's a fish keeper and knows a lot about filters, and was the one to install it). But, there was just too much poop.
I've found that, for my--up to 20--ducks and my amount of land, that the easiest thing for me is to have 1 or 2 trays of water that are 1-2 inches deep, and 1.5-ish feet wide and 2.5-ish feet long. I dump these out every day and refill them. During the summer, I move them around by fruittrees, so that when I dump the water, it fertilizes and waters the tree. Because I dump the water every day, it doesn't get icky, and since the trays are small, the ducks can't make as much of a mess, and they don't need as much water. I also provide my ducks a pail to drink out of, so they can clean their bills easily. I change that water every day, too.
Ducks are SO good at making duck poop. It's really impressive.. and a little duck poop goes a long way to making a pond gross.
I am guessing a substantial sand/gravel filter is the only economical filter option, you'd want a lot of media... these can be DIYed in 55gal barrels...
I think planning to use the duck water for plants, replacing often, is much preferable, unless you have a really dire water shortage and no way to add storage to compensate... in which case, maybe not ducks..?
If I end up raising ducks here, I will plan to both rotate them between ponds, and to pump hundreds of gallons of ducky water onto plants, replacing from another pond as needed...
If it's a stationary pond, I would use a couple of raised-bed filters. I would construct stands for two halves of a 55 gal. drum, take a whole drum and cut it down the middle, so you have two half-cylinders.
I would drill a few drainage holes in the end of each, near the rounded bottom edge, raise the other end of the half-barrels slightly, and drop a coarse pebble into the bottom, perhaps with a biochar layer sandwiched between landscape cloth, and topped with a garden bed.
I would make a slight partition of landscape cloth at the raised end of each half-barrel, and fill the partition (not large, just enough for the purpose) with a sand-filter arrangement, into which a pump can deposit duck water without washing away the garden soil. The pond water should flood the surface, but not so much that it overflows or displaces soil. A layer of sand might do well between the landscape fabric barrier and the topsoil.
I would plant heavier-feeding plants near the sand filter end, and those requiring less would go nearer the drain.
If the lower lipped ends are left to drip back into the pond, the water will be clean by the time it reaches the pond again.
If you want to grow plants that the ducks aren't to eat, why grow them where the ducks are going to be?
I wouldn't put anything in your duck pond that you don't want eaten. In fact, I would probably encourage the growth of duckweed. You could grow aquatic plants that ducks do eat, but screen off the main plant so they don't kill it completely, but can easily eat anything that pokes out of the protective screen. In that way, the plants will grow back, to be cropped back again by the ducks.
As to fish, I would add some white cloud mountain minnows (I think that's what they're called) to combat mosquito larvae, or anything else that you don't want overrunning your tank. I would also get a bottom feeder. My choice would be a local small catfish, brown bullhead, but you might have other choices available. Koi might actually do the trick, if you're uninterested in eating them.
You might want to consider making a long sock-like arrangement to contain some kind of growth medium, even silt and muck from a natural pond local to you. This would be hung just under the water level around the inside rim of the pond, and you would want to plant a local reed bed guild in the sock. It might require a little additional protection, but you could have a ring of reeds around your duck pond, giving them shelter and seclusion from predators, and the reeds would actively filter the water, reducing the load on any filtration method you choose that requires a pump.
There are many options. All you need do is tailor an approach to your specific situation. Let us know how it goes, and good luck!
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