I ditto tiller and others. Good advice from all so far. The only thing I would add about chemicals...is that there is one bottle of stuff you really should have, and that is a water treatment for Chlorine and Chlorimines. Chlorine is not that bad if you add less than 10-20% of your total amount at once. The fish can get Gill Burn if they play in the hose spray so put the hose in a area they can't get to. The chlorine will hurt your bacteria colonies in your bio filter but won't wipe em out. After a day or two contact with the air will dissipate the chlorine (it will go faster if you have an airator or waterfall). Chlorimines though are baaaad. They will never leave your pond without being treated with an additive. You can call your water company and see if they use chlorimines. If they do, then you need to get in the habit of using a neutralizer every water change. If they don't then you can get away without, unless you notice your plants being hurt by chlorine when you change the water. "Bad stuff" on the bottom are organic compounds like leaves, fish poop, dead fish etc. As it decomposes it will create a layer of mud called "muck". It's black and smells bad. If your pond ever has a sewer odor that's a sure sign that your muck has run amok and the fish are in danger. When this happens oxygen levels drop and you start getting brown algae and your water will look like rootbeer. Anaerobic bacteria start to go to work in the oxygen free environment. This is a fish death sentence. You should regularly scoop out the majority of the muck leaving as little as possible on the bottom after it settles back down. "Regularly" depends on your pond. More trees, dust, pollen, weaker filter etc mean you need to clean it up more or less than others. There is no rule about how often to clean. To clean out muck, you just need to scoop it out. You can do that by hand, with a bucket or shop vac. One thing I like is this little attachment that goes on the end of a garden hose. The flow of the hose water creates venturi suction that pushes the muck into a little nylon bag. Keep in mind that with any of these options you will stir up the muck and it will take a day or so to see improvement. If you do it regularly, the stirred up muck isn't a problem for the fish. But if you have a deep layer of it you might want to do what destany said above, and move the fish into a container for a bit (filled with pond water!) as all those bad compounds will be spiked during the clean. If your depth is closer to 3 feet I would still think about either getting rid of the goldfish (donate them to a pet store or other ponder) or the koi. With either 3 koi or 11 goldfish you have about the right fishload. But with both, you have about double what you will need in a year or so when they get big. If you are dead set on keeping all of them, you need to plan on losing some to stress or plan on getting a heavy duty biofilter and/or doing regular muck sweeping.

You may not have a problem at all. Is your worry about stagnant water that will trap debris and rot because nothing ever leaves that zone? Or is it just a worry about getting surface gunk to your skimmer? First I would doubt that if I have a correct picture in my head that the water could actually be "stagnant". The surface may be calm and appear not to flow things to the skimmer there properly, but there likely a lot of circulation under the water (especially if you have a bottom drain). Are there fish in the water? You could use a fish safe dye to see if water truly does sit there. Pour it in the stagnant area and see where and how quickly it mixes out to the rest of the water. If the dye hangs around that area a long while then you do have stagnant water there. If the dye mixes under water quickly but not on top, it just means you have a calm surface but no real stagnation issues as the current will be sucking things under the surface toward you bottom drain. A big river can be swift moving but appear still on top. Is the real issue a worry about how to get leaves or other debris out of this area? If you dont have a big leaf problem the calm area may actually be a great place for lilies, water hyacinth, water lettuce etc. I actually have the opposite problem in that I didn't leave a calm enough space in my bottom pond to grow those plants. However I have a horrid...horrid leaf problem in fall and prefer the optimal skimmer to having floating plants when the wind starts blowing my leafy plague of doom down from the trees.

Thank you so much! I guess I'll just keep an eye on it for now. It was there the last two summers but this year it seems to really be taking off. It's easy enough to pull up if it gets too thick. I'll just be sure to wear gloves and long sleeves!

I am just getting a pond started and need some help. I will pay postage for any pond plants that anyone has extra. I do not have anyhing except christmas cactus cuttings to trade but i have 3 diffrent colors of them. Red,pink yellow.I appreciate any help i recieve thanks.