Digging the Hole
How to Build a Koi Pond, Goldfish Pond or Water Garden from the Ground Down

   
     
Once you have decided where you want your goldfish pond, koi pond or watergarden to go and you've done your homework with choosing and purchasing the equipment for the type of pond you are building -- you have no excuses left to delay breaking ground with your pond construction project.  Yes, it's hard work but it's exciting to watch as your pond takes shape.

Change into some old clothes.  Put the beer on ice for later.  Grab a shovel and let the digging begin!

  • Check for Utilities
    Before sticking the first shovel into the soil be sure you are not going to hit any electrical lines, gas lines or water lines.  We hit our main water line at the water garden center and it was not a pretty sight!  It set us back with time and expense.  The utility companies are often happy to come out and mark the lines.  The gas line, of course, is the most dangerous one to hit for obvious reasons so your homework here is very important!

Rent a Back Hoe
Unless your pond is small (less than 1500 gallons) I would invest in a back hoe or some kind of motorized digging machine.  Size the machine to the job.  We needed a heavy-duty machine with operator included for our 15,000-gallon koi pond.  You might not need something that elaborate.

  • Help Wanted (or Maybe Not)
    If you are a big, burly kind of guy with lots of buddies willing to jump in to help you may not want to hire day labor but if you are like me you wouldn't last an hour out digging in red Georgia clay.  Day labor is a beautiful thing!  Hire muscles - not brains and hire at least two strong people.  Make sure you have as many digging tools as people.  Stay close and supervise them because they don't know what you are wanting - only you do!  We have left day workers to dig a hole and come back to find that they tunneled down to China!  Your pond doesn't need to be that deep...  Oh, and you probably still need them even if you rented a back hoe because the walls, shelves and floor of the pond need sculpturing after the initial dig. 

Draw your Pond.
Use a rubber hose or spray can of paint - there's some bright orange landscaping paint that works wonderfully that you can find at Home Depot or Lowes - and draw the outline of the pond.  You might start with a hose that you can change around until you get the right look then spray-paint the shape for a more permanent outline.  Hopefully during the designing phase of your pond building project you would have already pre-calculated the size of your pond so make sure you measure the hole so that you get the most out of your liner.  You might also outline where the shelves will go and write the depth of each section.  Be creative!

  • Dig In!
    Begin the initial dig with your motorized digging equipment.  Dig down to the deepest end and around the sides as much as you can without compromising the structure of your pond.  If you plan to have a rock shelf around the perimeter of the pond I would wait and do that part by hand.  Then jump in with shovel in hand (or instruct your workers to begin) and sculpture out the walls, the shelves and the floor of the pond.  If you are building a waterfall the dirt that is removed can be used to help build it up so mound it up as close to the waterfall area as possible.  If you are going to use the soil in a garden or elsewhere in the yard you can certainly take advantage of strong day labor to relocate the soil.  Cover any mounds of soil that you have with a heavy tarp in case of rain.  You will NOT get around to doing the waterfall the same day as you dig - I assure you! 

The Depth of the Pond
If you are planning to have fish in your pond, whether it is goldfish, koi or some other type of lake fish, do yourself and your koi and goldfish a favor and dig your pond (or at least the biggest portion of) 3 ft. deep or more.  This is to protect the fish from blue herons.  You may have never seen a blue heron in your life but the moment you place an expensive koi into your pond will be the moment you see your first blue heron - and he will be flying off with a magnificent wingspan and your koi in his mouth.  They are prolific all over the US and other countries as well.  Blue herons will walk around in 2 1/2 feet of water and can easily clean your pond out of fish (and frogs) within a few days!  The 3 foot depth will give the fish a fighting chance.  If you are building a koi pond 4 to 5 feet depths are even better.  Koi get their exercise by swimming up and down, not by swimming side-ways.  Plus - the more depth, the more water.  The more water, the less problems with water parameters.

  • Koi Pond Considerations
    A true koi pond has special construction considerations that must be addressed when digging the hole.  The depth is a concern, of course, and it should be at least 4 feet for large koi-keeping.  Plants and koi do not really go together in the same area of the pond.  I've seen waterlily blooms sail across the water and find that a frisky koi is the culprit.  They also wallow a lot in the soil of plants and create a mess.  Goldfish tend not to be as destructive to plants though they can and do also wallow in the pots.  Plant shelves are not a good thing in a koi or goldfish pond either because they create a dining table for raccoons.  Raccoons eat fish as part of their natural diet and koi and goldfish are delicacies.  Skip the plant shelves in a true koi pond.  If both water plants and koi are desired I would build separate ponds for them.  The walls of a koi pond should be slanted very slightly toward the inside of the pond.

Plant Shelves
If your pond is more of a water garden than a goldfish or koi pond you will want many depths of shelves.  Lotus pots are generally about 18" tall and the water should come "just over" the top of the pot.  The best thing to do if you are planning to place a lotus plant in your watergarden is to buy the lotus first!  That way you can construct a custom shelf for it.  Be sure, however, to keep water in the lotus pot so the plant will not dry out and die before it is set into the watergarden.  You might want to make shelves at 1 ft. of depth, 1 1/2 ft. of depth and 2 foot.  This will give you an assortment of options where to place plants in the pond.

Water lilies are a whole other issue when it comes to the depth needed for their best performance.  Large hardy varieties go on the floor of the pond in larger pots so they can produce large blossoms and pads -- even if the floor of the pond is 5 feet deep!  Tropical varieties need the warmth of the sun so they should be placed about 1 1/2 to 2 ft. max.  Dwarf varieties should be placed about 1 1/2 ft. down.  Most marginal plants go about a foot down so the water level goes just above the rim of the pot.  Umbrella palms are an exception.  They can be placed in large pots down to 3 feet of water but do best at around 2 feet.

  • Let Me Level With You...
    The most important consideration when digging and sculpturing the hole for your goldfish pond, koi pond or water garden is to make sure the edges of the pond are level.  If the pond is not level it will show up like a sore thumb! Take a string leveler and attach it to both ends of the pond on the highest shelf or the ground if the water line is to come up that far.

The Rock Shelf
To best way to naturalize the edge of a pond is to build a 1/2 ft. high, 1 ft. wide shelf around the perimeter of the pond.  The liner would go over this shelf and the water line would come up about half way so you don't see the "wall" of the pond as clearly.  This is where you would place large rocks and boulders and you could even tuck water plants in-between the rocks.  The best types of plants for this marginal area are ones that spread out such as water fringe or variegated water celery.  During the digging process you would need to carve out that shelf.  If you are planning a waterfall you need not carve the shelf under the area where the waterfall will go.  A rock shelf will not show a pond that is off-level as much as one with no shelves around the perimeter.

  • The Walls and Floor of the Pond
    The floor and walls of the pond can be sculpted to encourage a cleaner pond that requires less maintenance.  The walls should be slightly slanted toward the inside of the pond.  This will help guide debris to the bottom drain or water pick-up.  In fact, the whole floor of the pond should slant ever-so-slightly toward the bottom drain area.

Stairway in a Pond
Here's something we wish we had incorporated into our personal koi pond!  Ponds over 10,000 gallons can be hard to get in and out of!  Our 15,000-gallon koi pond is simply wonderful for the koi but if we want to get into the pond (or, more importantly, OUT of the pond) we better have a lot of upper body strength to hoist ourselves up and over the edge.  Looking back, we wonder why we simply did not design a set of stairs into the pond.  Such a simple idea!

 

   

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