One thing that I know for sure is that if you keep Koi, you're going to have to acquire some knowledge of how to outfit you're pond with a few essential supplies.
  You want to keep these fish happy and healthy.
If you want to give your yard that serene and tranquil feel, a good idea is to place a fountain in your pond.
  Not only will this oxygenate the water, but will also get rid of unwanted surrounding noise.
  It will give some motion to the water, and will keep the fish entertained and exercised.
One thing that I've personally noticed is that the filter in my pool is essential.
It needs regular maintenance and upkeep to keep the water clear.
  The filter is one of these indispensable supplies that remove the unhealthy particles detrimental to the Koi.
  If you've got a filter, then you need a pump.
  Some of you will say that you've a got a pump in the fountain that you just put in.
  That doesn't cut it.
The fountain pump really isn't strong enough to do the job.
  You need to have some motion in that water so that it will actually force the liquid through the filter.
  The entire health of your upon depends on a good pump.
Dechlorinator is another essential supply that should be kept close by.
  If you are on a city water source you can assume that they add chlorine.
  Fish and chlorine don't like each other.
  Dechlorinator will remove the harmful chemical from your water supply.
  Another thing that you should check regularly is the pH and nitrate level in your pond.
  The test kits are easily available at any pet supply store that sells aquariums.
  Think about adding some pond salt and baking soda to regulate the pH and nitrate levels of the water when your test results show that the pH levels are off.
Another thing that you have to watch out for is that Koi will attract natural predators.
  Cranes, raccoons, household cats, and even dogs have been attracted to what they saw in my outdoor pond.
  When you're first designing your pond try to keep the water deep enough to prevent a heron from standing in it.
  A good idea is to create an overhang high enough to prevent any of these critters from actually reaching the water.
  If you decide to put your pond under a shade tree the birds won't be able to see it from above.
  One thing that I've done personally is to actually put a net across the entire pond.
  It doesn't always work, because some critters are smart enough to chew through the netting, but it might give you time enough to spot the little thieves and chase them away.
  One thing that the net does well is catch the falling leaves and keeps the pond clean.
Of course, the food is the most important supply.
 At least the Koi thinks so.
  Keep some of the food fairly close to the pond.
Especially what the Koi considered treats.
 You can entertain the Koi, by feeding them out of your hand.
  I'm always amazed at the first two or three brave ones that rush to my corner when they see me approaching.
  I find that these fish delight and entertain me with very little effort on my part.