Information About Ponds and Plants

Information about Koi, Hardy and Tropical Waterlilies, Lotus, Watergardens, and Koi Ponds

Interesting facts, comments and articles about the outdoors and the environment

When I copied this over from my old web site, I carried a few glitches. As time allows, I will go back and fix the links, titles etc. Sorry if it is a little hard to read.

The Beginners Pond Page

If you are new to the idea of water gardens or fish ponds read on. You can use the hyperlinks below to go to the specific section of the document. If you choose to print out a hard copy, you will get the entire document which is about ten pages long ... Reviewed and updated ... October 2004, November 2005.

This document is organized for the beginner as follows:

1. The Difference Between a Koi Pond and a Watergarden

2. How Deep, How Big Should My Pond Be

3. Should I Use Concrete or a Liner ... and what about a Bottom Drain

3a. Digging the Pond     (not all these links are connected yet 2 292008)

4. Some Thoughts about Plants

a. Soiless Potting Medium

b. Plant Shelves

5. Filters and Pumps

6. Homemade Filter vs. Commercial Filter

7. Springflo .. a Biofilter Material

8. Bubble Bead Filters

9. Sludge and Muck

10. Watergardens ..

11. The Generic Koi Pond

12. Some Rules to Follow

13. Some Mistakes We Have Made or Observed & Other Odds and Ends (never finished)

14. If You Got This Far, Maybe you will want to look at our Fish Index ... for more advanced topics.

1. The Difference Between a Water garden and a Koi Pond

In recent years watergardens and Koi ponds have become more and more popular. Water features and stone work are becoming a part of many people's gardens. As in so many new ventures people seem to make the same mistakes, and it is our hope to provide you with some very general information that will keep you from making the same mistakes we and many others before you have made.

We feel that the first thing you need to do is decide if you want plants, fish, splashing water, a water fall, artificial stream bed or all of the above.

There is a distinct difference between a water garden and a koi pond. If you strictly want water lilies, lotus, and water iris or other aquatic plants then you could have a gold fish or two (probably turning into a hundred) to keep the mosquitoes at bay. Your pond could be relatively shallow (1 to 1 1/2 feet) and in time would accumulate a couple of inches of litter on the bottom. In most cases the water would be clear except when stirred up by some mechanical means such as using a muck net to try to clean out the leaves and other stuff . You will get turtles and frogs in your water garden at some time, so you can count on them stirring up the muck too. If you want water lilies the best depth is from 12 to 16 inches deep. If a large plant such as a tropical night bloomer is in the pond and the pond is real shallow, the leaves will spread out very far apart.

Koi and goldfish

If you think you would like to have fish in your pond then you have some other decisions to think about. A few goldfish could be in anybody's pond, but if you want koi, and just about everyone does after they see a few of these beauties swimming about.

Koi are Japanese colored carp and have barbels on their chins which show they were originally bottom feeders. Koi love to root around on the bottom or in your plant containers if you have them. Higher quality koi require better quality water, and the water must be filtered properly. Koi also do better when the water is deeper because it gives them more room to exercise by swimming from top to bottom as well as along the length of your pond. The water will stay a more constant temperature the greater the volume which is something else the koi like. A very shallow pond will heat and cool rapidly especially in the winter and the koi will become stressed. Stress promotes disease problem. which are worse in the fall and early spring.

Garden variety koi are a little less fussy, and they become friendly pets that will eat from your hand. You will want their home to be clean and large enough to maintain them in good health. In a water garden it is a good idea to have at least a few goldfish simply to control the mosquitoes. Koi fry will also eat mosquito larvae.

You can buy "garden" variety Koi for a few dollars at a pet shop when they are three or four inches long. We bring in SELECT Koi which have a much better potential to grow into beautiful fish, and they cost $30 or more for a four or five inch Koi. The first year after acquiring a yellow butterfly Koi which would have been one year old when we got it, turned into a beautiful yellow fish with long flowing fins and tail. At the end of its second year it was about 16 inches long; in 2000 Merlin who then was renamed Merlene was approximately 24 inches long and a beautiful fish. Merlene turned out to be female so hence the name change. Unfortunately, Merlene died after I did something stupid in 2003. Koi commonly grow to 24 inches and live 50 years or more. In Japan they are passed down from generation to generation, and the oldest koi on record lived to be over 200 years old. See the story of Hanako.

2. How Deep and How Big

If you decide that Koi would make an interesting focal point and addition to your garden then your pond must have certain minimums. We have raccoons in this area (Piedmont North Carolina) and they can clean out a fish pond in nothing flat. Raccoons hands are prehensile, and if they stand in 18 inches of water they will reach under the water and feast on your fish. If the gold fish and small Koi have hiding places among the plants then they might escape, but Koi need deeper water, and the accepted depth in the USA is about four feet. It is a good idea to plan your pond with structure such as stacked rocks or a terra-cotta drain pipe.

A shallow pond heats up a great deal in the summer in the southeast, and the greater water volume will keep the Koi cooler which the fish like. The sides of a Koi pond should be straight without shelves, and sharp edges such as those made with jagged stone should not be permitted. In their natural state Koi love to root around on a mud bottom and have two "barbels" on the side of their mouths which are sensing organs. Even though we keep the water crystal clear to be able to observe the Koi, they still have the urge to root around and will do so in plant containers. For that reason if you have plants in the same pond with Koi you must protect the soil by putting gravel on top of the soil. Even that will not always work and creative Koi keeper have developed other deterrents. For instance larger rocks are placed on the gravel layer so that the Koi can not get to the gravel. Plant stands can be made from bricks, latex- treated cinder blocks, PVC and many other items. Make sure the stands do not have sharp edges which is why we do not use treated cinder blocks any more. I have seen koi and plants get along quite well, yet at the same time I have seen lots of gravel on the bottom of the pond that the koi pulled from the containers. If gravel will create other problems with your filter, pump, or bottom drain, you need to think about that ahead. In general, if you put a few koi in a pond with plants they will do ok together. If you put a plant in a pond with a great deal of koi, the koi will have a field day. When the new growth of a water lily starts in the spring, it is small and succulent, koi find that growth very tempting. We have designed ponds with stone walls separating the plants from the fish area. We allow small fish to go through the wall, but make the openings small enough so that the larger fish can not move between the two areas.

3. Should I Use Concrete or a Liner ... and What About a Bottom Drain

Koi ponds are frequently made using 45 mil EPDM liner which looks like the inner tube from a tire. This seems to be the standard although many older ponds were made from concrete which seems to crack fairly frequently. The liner ponds are guaranteed for thirty years or so and sometimes liner is placed under concrete or gunite which is the material blown in for making swimming pools. In earthquake prone areas, I believe that EPDM liner ponds are the norm. Cement ponds (actually concrete) now have fiber additives and bonding agents mixed with the cement to reduce the problem of cracking.

Many do-it-your-selfers will use the preformed ponds that one can be purchased at the large discount stores, but generally they are better for watergardens than koi ponds. It is difficult to hide the top edges of preformed ponds, but they do serve a purpose to the hobby. In recent years Savio and Aquascape and others have made pond kits for certain sized ponds. Eleven by sixteen is a nice size for a backyard pond and it efficiently uses a liner that is 20 feet wide. We often advocate deeper ponds than two feet if you are planning to have koi so that needs to be taken into consideration. The pond kits such as Aquascapes are great for watergardens but might not be an ideal depth for koi. We are always available to help with these decisions, so contact us by email or phone. 704-618-6214 jack(removethis)

One general rule that we like to use is to insist that a bottom drain is installed in almost any pond. This drain is often hooked up to a pump and filter outside the pond, but it does not need to be anything other then vented outside the pond with a valve for opening and closing. Debris will tend to settle in the lowest part or the pond, and if you open this drain and remove some water from the pond you will flush much of the sludge and waste with it. There are very good bottom drains that are designed for easy installation to EPDM liner ponds. If you install your pond on a slope you can vent the bottom drain to air, if not you can use a device called a Standpipe.

More sophisticated filters, such as a three stage vortex filter or a bubble bead filter attach to the bottom drains and cycle the water constantly through a series of filters. There will be settling portion of the filter that will trap heavy solids, a mechanical portion that traps smaller debris, and lastly a biological portion that will grow beneficial bacteria that convert ammonia to less harmful compounds. In recent years bubble bead filters have improved in that they handle larger loads and have backwashing capabilities. If you use a bubble bead filter, you need to make sure that the pump is sized properly for the filter. There are probably many reasons, but one is that there will always be a leaf trap in front of the pump to catch debris. If the pump is too small, the leaf trap will clog prematurely, and you will be forced to clean the leaf trap much too often. If the correct size pump is use, the force of the water will push small debris past the leaf trap basket and capture it in the filter where it can be easily flushed.

3a Digging the Pond

The dirt left from digging a pond can often be used in constructing the waterfall or water course. In our area, the clay is very hard, and it is possible to dig straight sides for the pond. In some parts of the country with sandy soil, it is difficult to keep the sides from falling in while the pond is being built. This could be true where the pond is being constructed on fill dirt. When collapsing sides are a problem, one technique that I have read about is to use 4 x 4's as post with a half sheet of plywood on the outside of the post. A sheet of plywood is 4 x 8 so since many koi ponds are 4 feet deep, that could work out well. Once the pond is full of water, the pressure of the water will be against the plywood. Slightly sloping sides that taper to expand at the bottom will also support more weight such as rocks and boulders. When you install the skimmer and waterfall unit, it is important to tamp dirt since when these devices are full of water they are quite heavy and can tilt in time. We had that happen once and water slowly went over the back of the filter and created a monster bubble under the liner.

Venting Water from Underneath the Pond

We always provide a way for water to escape from under the pond liner. It can collect from rainfall, leakage, and other reasons. We have heavy clay and this will only be necessary when the soil is not porous. I imagine that in sandy soil water bubbles underneath the pond is not an issue.

Hydrostatic Pressure

If you have ever squeezed a handful of mud or clay you know it moves laterally. If you visualize the wall of a pond that has turned to mud because water accumulates on the outside of the liner, you can also see a potential problem. The dirt above the mud and probably more important, the stone that is on top of the dirt provides a great deal of weight on the mud which has now turned to a dense fluid at the bottom of the pond. The heavier mud will first bulge in on the bottom of the liner, and since it weighs more than water, it will try to displace the water and the wall will come tumbling down. Remember that the stone we typically use for ponds is decorative and does not provide structural strength.

The above situation will not happen if water does not accumulate at the bottom of the hole outside the liner so obviously, pay attention as to how you can provide drainage away from your pond, as described above. Also if the pond is installed in dry weather, anticipate what might happen when it really rains during another season of the year.

Probably the best thing to do is install a drain on the floor or the pond under the liner. We do this by digging a very shallow trench filled with gravel and putting a piece of one to 1.5 inch PVC with holes drilled in it in the trench. Once this is out past the pond wall and directed upward, the water level in the pipe will be the same as the pond.

If you do have a place you can drain the water that comes from the hydrostatic drain you can make a drain that will work. Turn the pipe 90 degrees when you are about a foot under the water level of the pond . Extend the pipe to a pit that you must dig. We usually dig a pit that is a cube about 3 feet on the sides. This is probably overkill but it all depends on how much water gets in the bottom of the pond. In this pit we put gravel and then about 6 inches of soil on top of that assuming this is in a grass area.

The sides of this hole which you could refer to as a French drain allow the collected water to be absorbed slowly. You could accomplish the same thing by making a narrow but long hole as with a trencher, but the important thing is that you allow a way for the collected water to dissipate in the soil.

We have had ponds that just collected a little water infrequently, and ones that seem to have a constant seepage into and below the liner.

If you have a slope you can drain this hydrostatic drain to air, but we are not always able to do that. A couple of other issues come to mind. Clay soil which we have creates these problems. If your area is sandy then any excess water will likely just drain down below the pond.

Besides using a hydrostatic drain pipe, we have built a sump with a pump to keep water from collecting at the bottom of a pond. We found water under a liner with no place to go and simply dug a hole for a 3 inch pipe down the side of the pond on the outside of the liner. Another short note is that gases from decaying plant material sometimes will get under a pond liner and cause bubbles. Installing a piece of PVC pipe with holes in the bottom of it next to pond with questionable drainage would be a good idea. One could poke a stick down the PVC like a dip-stick would check oil on a car to see if there is an accumulation of water.

4. Some Thoughts on Plants

The common understanding is that Koi and plants are not compatible, but that is not totally true. It seems when there are lots of plants in a watergarden and koi are added, the koi leave the plants alone, especially when there is plenty of food. Also, if one feeds the Koi frequently, they seem to have less inclination to bother the plants. They will eat the roots of water hyacinths and sometimes the entire plant. If Water lilies can be placed close to the surface of the water the larger Koi will leave them alone most of the time.

We have found that gravel alone will not keep Koi, frogs, or turtles out of the plant container. Some success is achieved by using three or four flat stones over the gravel . As our fish grew larger, I prepared plant containers so that they were on raised platforms that would place the plant an inch below the surface of the water. I then placed flat thin stones in the edges of the pot facing up, and that kept all the fish on the outside of the container. I found this particularly useful with iris and other plants that liked to grow in very shallow water.

Soiless Potting Medium

In 1996 we started using SPM manufactured by Misty Mountain Farms. That stands for Soiless Potting Medium, and is made from coconut fibers. It is an organic so breaks down with time but it comes in a large roll and is about 1 1/2 inch thick. What we do is cut it into squares that are slightly larger than the container. We than take a rooted water lily and wash the dirt from the roots. Then a few stones are placed in the bottom of the standard three holed nursery container. Over that we place a couple of layers of potting medium and finally on the upper layer we cut a slit to the center. After placing the plant in the container and spreading out the roots we put the last layer of potting medium around the plant so the center of the plant is more or less in the center of the pot.

Lastly, we place a few stones on top of the last layer of potting medium so that the larger fish can not get in and investigate our handiwork. Originally we had some good success, but it seems to work better on well rooted and established plants rather than babies. If the stones are too high in the container, there is a tendency for the pot to turn over. The Koi seem to like to do that. If the lilies are grown out of the pond and then placed in a protective structure such as a PVC frame with net attached, then there should be less problem with the Koi eating them.

Some plants receive enough nutrients from the water so they do fine with SPM. Others that are heavy feeders do not (or at least we have not been able to figure it out.) If you would like to read a little more about SPM, check out Misty Mountain Koi.

Koi will knock over small plant containers, and except for being heavy to move about, larger containers are better because they hold more dirt and the plants seem to grow better and larger. If you have nice koi there is some concern that having soil in the pond hides aeromonas bacteria and some treatments which you might choose to do will not be effective. I have found that the occasional pot that was tipped over or rooted in by a koi was an extreme inconvenience and have chosen to have few plants and very little if any soil in the pond.

While we are discussing Koi and plants I should mention that if you want to keep them in the same pond, then parts of the bottom of the pond should be flat so the plant containers will rest properly on the bottom. The best drains for the ponds and water gardens are bottom drains, and the sides should slope toward the lowest point where the bottom drain is. This usually means that flat areas or shelves would be on the edges of the pond. We have had our pond for about seven years now (12 years now in 2004), and we have never cleaned the bottom. Occasionally leaves will get stuck behind a plant container, and we will net leaves off the grate over the four inch bottom drain opening. If you want to see more details about our pond check out Our Pond.

Plant Shelves

For me plant shelves around the perimeter of the pond seem to create a problem. Generally they are better for a Watergarden than a Koi pond. If you have sandy soil, or loose clay, shelves can collapse. In softer soil, we like to use a concrete footing under the liner to support the stone which we usually use for the walls. If you do not support the stone effectively, it can settle and cave in on you or create a leak. Shelves are also very permanent, and I have yet to see a pond or pond owner where changes are not desired. ~Chuck Rush suggest using some cinder blocks (painted with latex paint) to support a board and place plant containers on the board. This allows one to make plant shelves different heights, creates places for small fishes to hide, and can be moved if you decide you want things in a different location.

Plant shelves take up pond volume also. Are you better served by having a slightly larger pond and installing plant stands where you want them? One of the designs we like is to have 1/4 to 1/2 of the pond shallow for plants and the remainder 3 1/2 to 4 feet deep with bottom drain. Plants can be placed in the entire shallow end and the koi can take their pick of going to the deep end or swimming among the plants. We install a concrete footing where the stone will be placed and also install concrete across the pond at the change in depth. By doing this we can be assured that the wall will that goes across the pond will remain solid.

If you have Koi, they can thrash about and are likely to injure themselves on milk crates, or cinder blocks. Although I have not done it, I think wrapping the block in a scrap piece of 45mil EPDM liner would improve the situation. One could actually glue the liner back on itself and prepare a whole bunch of concrete blocks at the same time. Do this after painting with latex paint. You should end up with a plant shelve support that is black and soft to the fish.

So you see some decisions need to be made early in your planning. Our advice would be that you get a book or two on Koi and water gardens from the library and read about the subject in more detail. Also there are lots of internet sites that are helpful too. Check our Links Page.

Because Koi are beautiful, they move around in your pond; you can even train them to eat from your hands. They become pets and do not have to be expensive to be enjoyed. We had a big yellow Koi that swam sideways. Later we found out that he only had one eye so we named him Cyclops and would not trade or sell him for the world. There are many other wonderful reasons we think everyone would probably want koi in their garden. Realistically, you must keep the water clean and consequently the water must be filtered.

5. More on Filters and Pumps Top

A surprising amount of debris ends up in the bottom of the pond. We strongly recommend a bottom drain be installed. One of our little rules is that if you can get the debris to the outside of the pond it is much easier to clean. In our 6000 gallon pond, we have never cleaned off the bottom of the pond. All debris ends up at the bottom drain and is carried outside the pond where all we have to do is shut the pump motor off, open a valve and we have cleaned much of the debris from the pond.

The typical small pond will have a submersible pump with a small "tub" filter affixed to it. After a time these filters need to be pulled from the pond and cleaned. I have talked to pond keepers who actually have to clean these filters as often as daily. After a time, this chore becomes tedious. Another reason for preferring an external pump is that a submersible pump can become a safety hazard since 110 volts and water are a bad combination. Admittedly, there have been lots of improvements in submersible pumps, and we use them often in skimmers.

A skimmer is a very handy piece of equipment that serves as a mechanical filter in that it removes leaves and other floating debris very well. In our situation, after the pond water goes into the skimmer the water is pumped to a small bubble bead filter which serves as an excellent mechanical filter. The bubble bead filter is a relatively new addition to all the items you can buy to keep koi happy. They are common enough now that they are referred to as Bead Filters. One of the real pluses of a BBF is that you can clean your pond entirely by opening and closing various valves and switches. If you want a pond with an easy to clean filter, the bubble beads might be for you. In the few years since we wrote this article, there are lots of new bead filters on the market. We know of Cyclone filters, Aquadyne, Hydrabead, Ultima II etc. just to name a few. There are lots of theories as to what type of filtering is best.

The way the Bead Filters work is that they have small beads the size of BB's or specially made plastic spheres that have lots of open spaces on them. The purpose for these spaces and for that matter the outside surface of the beads is that is where beneficial bacteria will colonize. It takes six weeks for these bacterial colonies to fully mature in a Bead Filter and that is assuming that you have fish in the pond to supply ammonia.

The extra surface area on the special spheres adds to the effectiveness of the media. While the filter is running, it is also trapping debris and this debris can be flushed out of the filter rather easily. These filters are easy to clean and can be done with out having to change into dirty work cloths. Also the controls are on top of all the filters and are not in difficult places to reach.

There are other new filters out there. One is called the Nexus which uses Kaldnes Moving Bed technology.

As I edit this in 2005, I see that there is information below that also deals with Bubble Bead Filters. For the time being I will leave it as is.

One should always use a Ground Fault Interrupter ( GFI ) on electrical circuits that are near water, especially when using submersible pumps. Our main pump however which is external to the pond is in a separate enclosure and is not connected to a GFI because we are concerned about it going out during a normal rain storm and leaving our fish with no circulation, oxygen, etc.

Homemade Filters vs. Commercial Filters

Creating a proper filter for a Koi pond can be home-made or commercially done and get pretty sophisticated. You should plan on your filtering requirements when you first decide what type of pond you want. There are many ideas on the proper filter, and we prefer using a three stage vortex filter although have used the Bubble Bead Filters frequently in pond installation. The vortex filter is more elaborate than most people have on their first pond, but you should know about them just to be better informed.

The first stage is a settling tank that is installed at the same depth as the pond. Water flows by gravity into this chamber in a circular motion and the solids sink to the bottom. The upper and relatively clean water then goes into a second chamber which has brushes (like large bottle brushes) which are fairly easy to clean by hosing off. These brushes trap lots of fine debris and fish waste. We have recently found that cramming them close together and forcing all the water to go through a "wall" of brushes works best. Lastly the water goes to a third chamber which has biological filter material of some sort. Over the years we have used various materials for the biological material. We have used coconut matting and found it is a little hard to clean, and it breaks down in a season. Since it is organic you can use it your garden or compost it.

A more durable filter material is polyester. In our situation this matting served as the biological filter and was flushed out with pond water. Frankly, it was fairly tedious to clean and we changed from that also. We do not use a garden hose with tap water because the chlorine will kill the useful bacteria. The non-toxic water now is pumped back to the pond directly or by way of a water fall and usually will go through an ultraviolet sterilize which kills the bacteria. The size of these chambers will vary with the size of the pond, and it used to be a fact that a large pond would often have a filtering system that was as expensive as the pond itself.

There have been some changes in the last few years that have made the filtering easier.

7. Bubble Bead Filters .. A State of the Art Filter Top

Another very interesting filter is called a bubble bead filter and the smaller model looks like a big hour glass and stands 6 feet tall. The newer model has the hour glass part enclosed so the whole thing actually looks like a water heater. There are many floating beads in it and as water flows up through this contraption debris is trapped. Since they first came out there are many variations as to size and shape, but the principals are the same.

Bacteria form on the small fiberglass balls and serve the purpose of a biological filter also. The beauty of the filter is that all you have to do to clean it is cut the pump off. Open a valve or two to drain the filter and you are done with your maintenance of the filter. You do not have to go in and clean brushes, or filter pads. The down side of the bubble bead filter is that if the pump is idle for 45 minutes or so the useful bacteria die and anaerobic bacteria multiply. There are those who believe that toxic material can be produced in the filter and can under proper circumstances be harmful to your fish. One problem that developed with the earlier bubble bead filters is that if the owner did not clean frequently enough, the beads would clump up in the top of the filter and needed to be broken loose mechanically. Since that time, many of the newer filters have air pumps, or water pumps or fins inside that force air or water into the beads to break them loose. (edited 2004)

There is also a tendency for the beads to pack if the filter is not drained frequently. If someone lets it go for a month, it is likely that the beads will pack. Some of the new models have a back flushing device on them that allows one to break up the packed beads.

We have a small bubble bead filter on our pond as a demo and I am impressed at how much dirt it cleans from the water every time I drain it. It is so easy to clean that I do so daily and it only takes two minutes.

A friend of ours who is California has some very good drawings of filter set-ups for Koi ponds, and if you want to take a look jump to Aqua Art. They are also listed in our "Links" page.

6. Springflo .. an Excellent Biological Medium Top

For some time we have been using Springflo as the biofilter material. I like it because it does not channelize. If you have cleaned filters before you know that as the debris begins to clog up the open places, the water chooses the path of least resistance. Springflo is a ribbon like material that comes in a box but unrolls into an incredible mass of biofilter. In our case I clean it about monthly although it probably does not have to be cleaned so often. Our pond is terribly overloaded with fish, and I take extra precautions concerning water quality. To clean the Springflo, I simply shake it around a little and most of the sludge falls right off the Springflo. If I am doing a thorough cleaning, I then lift up the mass of Springflo which is a couple of bushel basket full and lay it on top of the adjacent filter. There is a little sediment on the Springflo but lots in the tank. I hose our the chamber with its sediment and sludge out through the bottom drain. This entire operation takes about 15 minutes.

Interestingly, the Springflo can be left outside the pond in the air for 24 hours, and the bacteria are not destroyed. You might ask why one would want to do that and it is because sometimes I treat the pond with things that will kill the beneficial bacteria and it is wise to remove the Springflo temporarily.

Sludge and Muck

As we keep koi, we learn. Sometimes not a lot, but there is always something going on in the pond. One thing that has become apparent to me in the last year has been the amount of accumulation of waste in the pond. If you think about it, I have a 6000 gallon pond, lots of fish, probably 50. The exact number and size is not really important, since they grow so the bio-load is constantly changing. I do know from past experience that as I added more hard surface area in my biofilters for bacteria to attach and grow on that the ammonia, nitrites, etc. were easier to control. I also know that if I feed 1.3 lbs of food to these fish per day that I am feeding about 40 pounds of food per month during the warmer weather.

All of that food is not eaten, and it is not all captured in my vortex. Where does it go? It is trapped by the brushes in the mechanical filter and by the Springflo in the biofilters. There is a lot of it, it is organic, and will increase the ammonia level if it remains, and under anaerobic conditions the sludge will produce harmful compounds that can kill my fish.

It needs to be removed. You must design your pond so that places where debris collects can be cleaned easily.


So far we have talked about Koi ponds so its time to say something specific about watergardens. I think that a watergarden definition would be a wet area (bog) or pond that has aquatic plants in it. These plants would differ from normal landscape plants in that we generally place plants in the ground and provide water for them. Aquatic plants come in all shapes and sizes and grow in places that are naturally wet and sometimes bog plants even grow in standing water. Many bog plants produce flowers and others are rushes and grasses which generally produce inconspicuous flowers. There are aquatics that float on the surface and those that stay under the surface.

I think of a watergarden as a shallow pond with lots of plants, a few gold fish and no external filtering. The plants filter the water, the fish eat decaying plant material and algae. The plants in turn are supplied nutrients by the fish waste and the decomposition of organic matter in the water garden. There are also many other organisms that find there way into the water garden and in time balance occurs. In nature eventually a pond fills up with sediment and becomes a flat field.

A true Water Garden that is perfectly balanced does not need any filtering at all. An ecosystem is created, and the plants and small fish exist in harmony. Realistically, we still need to clean out our ponds and for that reason the job is much easier if one has a bottom drain.

The Generic Koi Pond

1. If you make the decision that you want larger fish (Koi) then you really should have a pond four feet deep. If it is 8 x 10 on the surface, you will have approximately 1000 gallons. If you only make it two feet deep then its 500 gallons, but your fish will be subject to raccoons and blue herons which are our main predators around here. Keeping koi in less than 1000 gallons does not seem fair to the koi so we usually recommend that koi ponds be over 1000 gallons. The greater the volume of water, the more constant the temperature. The rapid change during the winter can cause the water to warm and cool rather dramatically and this change stresses the koi. One other factor on depth is that the koi get better exercise when they can swim up and down as well as back and forth.

You can create a shallow end or add shelves for plants, but then you actually create more debris. We have found that tree leaves are our biggest problems and one would think that after they have fallen they would no longer be a consideration. Unfortunately, leaves seem to blow in all winter long and that is where the bottom drain comes in handy. We also recommend skimmers which catch to floating leaves before they have a chance to sink.

Most high-quality well-designed ponds have surface skimmers that remove leaves and that is good. Much debris and an amazing amount of fish waste will settle on the bottom. With a good bottom drain all that waste can be transported OUTSIDE your pond and trapped in a settling chamber as explained in the paragraph above about filters. By opening a waste valve on the settling chamber you can flush all that waste out without getting dirty.

2. You will probably need additional filtering and settling chambers or similar devices can be hooked up in series depending on the size of your pond.

3. External pumps are generally more efficient to operate then internal ones, and because they are outside the pond they can be serviced more easily. We like to use Sequence pumps.

Some Important Rules

1. A four inch bottom drain is what we recommend, and bottom drains work well with liners. We think a good rule is that your plumbing that is below the pond should be the very best and strongest you can get because you want it to last for many years. With a four inch-pipe, the flow is such that small fish can swim down into a bottom drain to hide but can and will still swim out. If the drain in much smaller, the suction is too great for the fish.

2. Always design your pond so that if it springs a leak in piping the entire pond will not drain down and destroy your fish.

3. Install an automatic cut off so if a leak does develop your pump will cut off and not drain the pond.

4. Have an automatic cut off for water refilling. We had a 300 gallon container with about 100 comets, and young Koi in it and were doing a partial water change. The hose with normal tap water which was chlorinated was running very slowly, but we still forgot about it, and it ran all night. The next morning all the fish were dead due to the chlorine. One man we heard about put a bulky kitchen timer in his pocket any time he was adding water to his pond or doing a water change by opening drain valves.

5. Make sure that the pump in the skimmer can cut off if the water level drops. Some pumps will burn up.

Mistakes We Have Made

1. We were building a pond for a client and the workers were instructed to not pile dirt right at the edge of the pond. The reason was that we were going to put in a bottom drain and would start our trenching right adjacent to the edge of the pond. It would be a simple matter of cutting a hole for the pipe for the three inch pipe that was supposed to be the pipe for the drain.

When I got back about a ton of dirt was stacked on the edge of the pond. I said not to worry that we would simply bore a hole with our trencher and put the pipe through the 6 feet or so of dirt.

It did not work out that way. The hole left by the boring attachment was just a hair larger than the three inch pipe. We spent hours trying to get the pipe through the not quite large enough hole and eventually did so by lubricating the pipe and dirt with water.

Our problem was that we got ahead of ourselves and it cost us a fair amount of time and money to the get that part of the job done.

Some Books to Read

Our best advice to the beginner is to read some good books on the subject of ponds. Here are a few we like.

1. The Rock and Water Garden Expert by Dr. D. G. Hessayon

2. Hobbyist Guide to Successful Koi Keeping, 1991, by Dr. David Pool

2. Tetra Encyclopedia of KOI, 1989, by Tetra Press. Although this is an excellent book, a great number of changes have happened since it was published.

3. Gardening with Water, 1995, James Van Sweden, Random House New York

4. Water in the Garden, 1991, James Allison, Tetra Press

5. Garden Pools, Fountain & Waterfalls, 1994, Sunset Books

6. The Complete Pond Builder, Helen Nash

7. Koi Health and Disease, Erik L. Johnson, DVM, 1997, Reade Printers, Atlanta Ga.

8. Koi Kichi, 1997, Peter Waddington

9. The Pond Doctor, Helen Nash

10. The Manual of Fish Health, by Dr. Chris Andrews, Adrian Exell, and Dr. Neville Carrington

11. Encyclopedia of Water Garden Plants, by Greg Speichert, and Sue Speichert

Some of the books above have some beautiful photos and illustrations that will be helpful to you in deciding what you might like, and how you go about achieving the look you want. For a lot of detailed information there is a great deal on the Internet. Use a search engine and look for Koi or watergardens and you will find much to choose from. Also if you like newsgroups rec.ponds on the Usenet is excellent.