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Build a Pond Article by Ken Becker

A Pond From Scratch


Watergardening is the fastest growing segment of the Garden Industry today. It brings great satisfaction to the homeowner and provides hours of soothing relaxation. If you are thinking of building a pond, this informative article will help you to understand the basics. While owning a pond can be somewhat trial and error, building it does not have to be.

Location, location, location. Choosing a suitable location for your pond is a vital consideration for a healthy pond. Therefore, plan carefully where you would like to construct your pond. Many people make the mistake of placing their pond far away from view of the house. Like any water feature, it can be enjoyed from both in and outside your house. Choose an area that is open with at least 4-6 hours of sunshine a day. Ponds that are near trees are naturally higher maintenance. Ponds that are under trees usually have a difficult time with both falling leaves and aquatic plants because of the shade. Since you do not want runoff to enter the pond unnecessarily, try and stay away from low spots in your yard where water seems to settle. It is always better if the water if moving away from the pond and not into it.

When you decide on a location for a pond you should also consider your neighbors. While most people like the sound of running water, the noise of a fountain or stream can irritate some people. There is also the consideration of any equipment that may cause noise. On the natural side, frogs can sometimes create an incredible level of noise that can disturb neighbors of their sleep. Last but not least you should consider the important subject of safety i.e. for children.

A further consideration is both water supply and electricity. Both are necessary for a pond and should be relatively close by. If treated, pond water can be tap water. There are dechlorinating products or hose end filters that can remove any chlorine that may be present in the water system. Well water is not suitable as it generally lacks oxygen and carries substances from various layers of the soil, which could be harmful to your fish. Always check the water quality before filling your pond.

Pumps and Filters

Check your local building codes to see how far from the pond your electrical outlet must be. It is important to choose the correct location for the filter and pumps to enable effective operation. Making un-necessarily long runs of pipe can cut down on the efficiency of your pond. Use the largest diameter tubing or PVC pipe that you can. Using 1/2" or 3/4" pipe will not allow enough water flow for most pond situations 1.25" - 1.5" is preferred or 2" pipe for larger ponds. Pumps and filters come in both submerged and in line (out of pond) We recommend a pond pump that is large enough to exchange all of the water in your pond hourly. If you have a 1000 gallon pond then you would need a pump that produces a minimum of a 1000 gph. Keep in mind that pump volume decreases as it pumps water higher so that if you have a waterfall that is 5' high it will reduce the flow of water. Other variables such as hose, fittings and filters also cause a loss of water flow. The volume of your pond can be calculated by multiplying the width x length x depth x 7.5 = number of gallons. You will need to decide how and where you want the equipment to be. There is a better selection of external pond filters and for larger ponds you might want an external pump for ease in maintenance. On the other hand, submerged pumps and filters are much easier to install as they have little or no plumbing and are preferred by novices. The other consideration is if you plan on using the filtered water to continue up to a stream or waterfall then you would need a pressurized filter. These are usually external cannister type filters that can be buried up to the lid. Because they are under pressure, the filtered water can be pumped uphill to your water feature. Some bio filters are gravity fed and the filtered water is just pumped directly back into the pond. This type of filter is not recommended for ponds with waterfalls unless the filter is placed at the top of the waterfall waterfall. Both types of filters are available with or without an optional Ultra Violet filter. UV’s have become increasingly popular as a method to eliminate green water algae and kill microorganisms that might harm your fish.

If you plan to install lighting systems you will also need to plan for that as well. There is an ample supply of low voltage 12V lighting on the market that can be used in and around the pond. Don't forget you will need to use an approved GFI (Ground Fault Interrupter) Never operate any electrical equipment around a pond unless it is connected to a GFI.

A Brief Recap

  • Choose an open and sunny location with at least 4-6 hours of sunlight. Do not construct your pond under a tree.
  • Choose a quiet place for a tranquil haven for wildlife.
  • Ensure the availability of both a water and power supply. Check for water quality.
  • Check the location for the pond, i.e. close to the house or farther away. Not in the low end of the yard.
  • Check with the local building department for codes about electricity.
  • Decide whether you want to use a pond liner, a pre-formed pond or to build one.
  • Determine what type of pond filter you will need, submersible or external.
  • Determine the size of your pond so you can calculate your pump size.
  • Determine the size of your pump. It should exchange all of the water in your pond hourly.
  • Ensure the availability of a water and power supply.

Building Your Pond

The decision for the size and shape of your pond is determined by your own preference, the size of the garden and the intended location. The size of the pond plays an important part for the biological balance of your pond. The larger the pond is, the more natural the visual effect, and the better the conditions for plants and animals. If you intend to keep fish, especially Koi, your pond shoud have a depth of 30" or more to provide an ideal living environment, especially in the winter. If you do not intend to maintain fish, your pond can have a depth of only 18-24". The number one complaint from new pond owners is that they wish they had made the pond larger the first time. Keep this in mind when planning your pond.

What Kind of Pond

Since the introduction of fish friendly flexible pond liners like EPDM, constructing your pond has become a do-it-yourself project that can be accomplished over even a single weekend. We are going to discuss this type of installation. You might also consider a pre-formed pond, a concrete pond or an above ground pond. After you have determined the size, you will need to purchase the liner material. Measuring for a liner is not complicated. You can purchase it in pre cut standard sizes or have it cut from a bulk roll. It is usually sold in 5' increments so that if you need a 16' x 19' liner, you would purchase a 20' x 20' piece. You need to measure the width plus twice the depth and then the length plus twice the depth. Always allow at least a foot or two for overlap. You should also plan on an underlayment. We recommend a non woven fabric that is made for this purpose. It will provide additional tear and puncture protection for your liner plus it helps in soil stability and erosion.

The most popular approach to building your pond is one that involves removing the dirt from the pond and utilizing the excess dirt to form a waterfall. It solves the problem of what to do with all that dirt you are going to remove. If you have a garden hose you can use it to lay out the shape of your pond before you measure and order your liner material. Then once the desired shape is achieved you can use spray paint or powered chalk to mark the ground prior to digging. You will need to decide if you are going to build your pond with straight vertical edges or have a shelf that you can place bog plants on. If you live in an area with predators you might consider a pond without a shelf or a pond that only has one in a small area leaving most of the pod without. This will keep out most land predators like racoons. If you elect to have a shelf, you will have a more aesthetic pond because of the addition of bog and marginal pond plants. It will also be easier to view your pond fish as they can come up to the step area for feeding. The choice is really yours to make. There is no right or wrong solution. If you choose to have a shelf then you should dig the entire pond down to the level of the shelf (usually 12") Then come back and mark the area in which you want the shelf to remain and dig out the pond another 6-12" where you could place another shelf. Finally, dig out the deep end of the pond and slope the bottom so debris will settle in one area.

Bottom Drain and Skimmers

Here comes another choice you will need to make. Larger ponds (3000 gallons or more) generally function better when they have a bottom drain. The only draw back to a bottom drain is the possibility of leakage. Most pond bottom drains are made to work with EPDM liner so there really should not be a problem. Follow the manufacturers directions for installation. Bottom drains can also be installed in conjunction with a pond skimmer. If either or both of these optional equipment is used it is better if you channel out the dirt on the bottom of the pond for the PVC pipe to lay in. Otherwise you end up with an unsightly bulge on the bottom of your pond. Use as large a diameter pipe as you can, usually 2-3". Lay the underlayment in the bottom of the pond and then carefully lay the liner in the pond being careful not to snag or tear it on any shovels or pipe. Pond liner is very heavy so it may take the help of several friends. Be sure that the pond liner is large enough to overhang the pond at least 12" all the way around. At this point you can weigh down the edges of the liner with bricks or heavy rocks and gradually fill the pond ˝ way with water. If you are using a skimmer, then connect it before you fill the pond with any water. The weight of the water will help the liner take the shape of the hole. I like to either use large flat stones to go around the pond and hold the liner or to build up a small burm. This helps keep out any ground water or runoff. First trim any excess liner and fold over the end before your cover it with stone or soil.

While the water is filling you can hook up the waterfall. This is accomplished by running a 1.5" hose to the top of the water fall from either the pond skimmer or the pond pump discharge. There are commercial waterfall containers that collect the water at the top of the falls and then evenly distribute the run off down the stream. This is a great option but not a requirement. These containers come with or without filter media and can also be fitted with a UV filter. You can also build up the top of the waterfall with large stones and have the water discharge thru them. I recommend that you use excess liner material to line the water passageway of your stream. This will prevent mud from filling your pond. Make sure the stream is deep enough so no water flows over the sides. You can then place rocks in and around the stream to give it a more natural look. Pond plants can be added for a more realistic effect. After the water fall is complete, fill the balance of your pond with water and start your pump. I like to install a ball valve on the discharge side of the pump so you can adjust the waterfall flow. Check to see that there is no water discharging from your stream or waterfall except into the pond. You may have to adjust your rocks to accomplish this.

A Brief Recap

  • Determine the size and shape of your pond. Measure for your liner.
  • Use a garden hose to outline the shape.
  • Decide if you are going to have vertical walls or steps in your pond.
  • Excavate the dirt from the pond. Use the dirt to build up for a waterfall.
  • Determine if a bottom drain or skimmer will be needed.
  • Place the underlayment in the completed hole.
  • Carefully place the pond liner over the underlayment.
  • Place stones or bricks around the pond liner to hold it in place.
  • Fill the pond ˝ way with water.
  • Install the waterfall.
  • Complete filling the pond and start the pump. Check the waterfall.

Plants and Fish

Aquatic plants play an important role in your ponds eco system. They help to provide oxygen for your fish and add balance to your pond water. They also compete with algae for nutrients in the water. In addition, some plants can actually help filter your water. Plants like water lilies provide shade for your fish and other plants provide a home for your fish to lay their eggs in. Aesthetically, they also will serve to help your pond blend in with the rest of the garden. No backyard pond should be without aquatic plants.

There are several things to know about pond plants. They are usually referred to as Hardy or Tropical. Think of this as Perennial and Annual. There are different categories of pond plants. Water lilies and Lotus are the plants that are most synonymous when you think of a pond. The blooms from these plants can be quite spectacular. There are also Marginal plants that are best used around the pond for added color and their roots can also remove nitrates and help to balance the water in the pond. Bog plants are used in the bogs or shallow areas of your pond in the same way as marginal plants. Submerged or oxygenating plants make up another category. They provide nourishment for your fish and add to the oxygen levels. Finally, floating plants such as Hyacinth or Water Lettuce act as living filters. Their roots remove nutrients and nitrates and add to the water clarity. Typically a pond should have 60-70% of the water surface covered by pond plants like Lilies or floating plants. This keeps some of the direct sun out of your pond and helps minimize any algae problems you might encounter. Be sure and check to see that the plants you are considering are not restricted by your state. Some invasive plants cannot be shipped into certain states. When planting your aquatic plants do not use common garden soil or planter mix as they can contaminate the pond. Since aquatic plants get their nutrients from the water and not the soil, the planting medium is much different. You can use plastic or clay pots filled with rocks for plants that will sit on the floor of your pond or purchase aquatic soil or in a pinch use clumping kitty litter (unscented) or washed gravel. In the growing season be sure and fertilize the flowering varieties monthly with fertilizer tabs. These are specially formulated tablets that do not increase nitrogen levels or cloud your pond. Pond plants need occasional trimming. Cut off any dead flowers and leaves so that they do not deteriorate on the bottom of the pond. Many of your pond plants can be cut down in winter and placed in the bottom of your pond for another season. Unfortunately, Tropical, submerged and floating plants usually are replaced annually.

Many pond owners end up with fish even if they did not originally plan to. There is nothing more relaxing than watching your pet Goldfish or Koi glide thru the water in your pond. With patience, they can even be trained to eat out of your hand. Never rush to put all your fish into a new pond. It is best to place one or two small fish in your pond and space them out over time. The gradual introduction of fish will help your eco system to adjust and if there is a problem with your water you will not lose all of your fish. Be sure that your pond water has been de-chlorinated before you introduce fish to the pond and that your pH is in an acceptable range. Purchase a simple test kit and test your water weekly for water quality. As a general rule, most pond owners overstock their pond which results in an imbalance in the water. The simple rule is 1" of fish for every 10 gallons of water. If you have a 1000 gallon pond you should no more than 100 inches of fish. The problem with the rule is that fish grow quite rapidly and your 100" of fish can be 200-300" in a single season. A better way to look at it is to say one medium size fish for every 100 gallons and one large fish for every 150 gallons. These are general rules and you will need to set your own.

You should feed your fish one or two times a day when the water temperatures are 76-80 degrees and once a day when it is 70-75 degrees. Never feed them more than they can eat in a few minutes. Fish have no stomachs so they always appear to be hungry. During the growing season (spring thru summer) feed them high protein diets for growth and color enhancement. During the early spring and autumn, switch to a wheat germ or vegetable based food as it is easier to digest. Most fish will stop eating by the time the water temperatures reach 55 degrees which is your cue to stop feeding them until spring.

Periodically adding pond salt to your pond is an inexpensive way of preventing fish diseases. Do not use salt that is made for water softeners as it contains added chemicals. If you live in an area with predators, consider the addition of a pond net. They are inexpensive and can keep both land and air predators away.

A Brief Recap & Other Useful Information

  • Hardy plants are perennial and Tropical plants are annuals.
  • Maintain 60-70% of your pond surface with plants during the growing season.
  • Fertilize your plants with plant tabs at least monthly during the growing period.
  • Do not use garden soil or planter mix as a plant medium.
  • Trim off dead leaves and flowers before they decay in your pond.
  • Do not add all your fish to your new pond at one time.
  • De-chlorinate your pond water and check your pH. Test your water weekly.
  • Add a “beneficial” bacterial product during startup and monthly during the growing season.
  • Do not overstock your pond - 10gal for each 1 in. of fish or 100 gallons for a medium fish or 150 gallons for a large fish.
  • Do not overfeed your fish. Feed only as much as the fish will take within 3-5 minutes.
  • Do not stop your pump and filter except for cleaning, as you will lose aeration and beneficial bacteria.
  • Do not place gravel or small rocks on the bottom of the pond as they will trap dirt, debris and fish waste.
  • Exchange 10-15% of your pond water monthly. This will flush out some of the harmful nitrates, ammonia, salt etc..

Remember, not all ponds are the same. Almost every pond is likely to be different, and because of the nature of the hobby almost every Pond Keeper will have different needs and ideas. What works for one Pond Keeper, might not work for others. It is far easier to build your pond correctly the first time than it is to try to change or modify the system later on.

This article was designed to cover many of the most common asked questions regarding building a pond for the first time. It is meant as a reference and gives a general overview of the subject. It is not intended to be a step by step guide. You are encouraged to buy a book on the subject that may go into more detail. If you have any further questions, feel free to contact us at info@pondiz.com . We welcome any comments or additions that you may have.

Happy Ponding from your friends at Pondbiz.com


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