Notes from Tetra Pond Seminar

Taken by Kathy Miller
March 9, 1995

While I was working at the nursery, I had the privilege to attend a seminar put on by the Tetra Pond people. It was geared for individuals working in nursery retail, but there was a lot of good information for anyone interested in setting up their own pond. I'm sure there was more there than I got written down, but what I have I humbly submit...

Contents of this page (click on subject to go directly there):

Types of Ponds

Initially, two kinds of ponds were described and discussed. Without the benefit of illustrations, I'll try to describe what was suggested. The two distinct types were the Koi Pond and the Lily Pond.

Because of the waste products which are more plentiful in a koi pond, it is important to construct it with a good drain installed in the bottom. In order for debris to feed to the drain, the pond should have sloping sides with the drain installed in the lowest point. The tube which provides an outlet for the drain (and is powered by a drain pump) should exit the ground 3" below the usual surface level of the water in the pond. The koi pond is constructed with shelves around the edges upon which you can place pots with marginal plants. These shelves should be approximately 5-8" below the projected surface level of the pond. Rocks can also be placed on the shelves if that is more desirable to the client. The suggested depth for the main part of the pond is from 3-6' with 8' being the maximum suggested depth. The fish will need good circulation in the pond so be sure that if you install a waterfall feature, it enters the pond on the side opposite the pump. You want to avoid "dead" spots in the water.

Since the purpose of the lily pond is to display plants, its construction is a bit different. The shelves around the edges should be 9" below the surface and the total depth about 18-24". The bottom of the lily pond should be flat to provide a stable base on which to set the pots. The pots in which you plant your lilies will be more suitable if they are rather wide and short. The water lily tends to grow much like a bearded iris. Instead of growing out from the center, they will spread in one direction. Plant them on the edge of the pot and direct them toward the other side.

For nursery sales, it was suggested that we should carry 80% liners and 20% preforms. The preforms provide immediate visual impact and are a good way to initiate the customer into the world of water gardening. Liners are generally more satisfactory, however, and to the experienced customer will be in more demand.

If you have questions about setting up a pond, read a good reference such as Garden Pools by Sunset. After giving the subject more study, you will usually want a larger pond than initially thought.

For good pond ecology there was a formula given (For every 2 square feet of surface):

When setting up a pond be sure to surround it with beautiful plants. Any kind of plant can be used depending on the type of pond...shrubs, small trees, grasses, ground covers, flowering plants.

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Liner Installation

The formula for how much liner you will need is this:

2 times maximum depth added to length and depth (plus a bit extra as margin for error)

When establishing the outline for a lined pond you can use a piece of rope or hose. This allows the customer to appreciate how large or small his pond will actually be in relation to the rest of his landscape. ( For instance, preforms tend to look much larger in a store than the pond that they create in the yard.) Use gentle curves in the pond. If putting in a waterfall, avoid one in the center which creates dead water. Put it on the side.

When installing the pond liner, be sure to situate the edges so that ground water cannot drain into your pond carrying contaminants and debris with it. This can be done by creating a lip with the liner which can be camouflaged by rock or planting material. Our speaker lost a $750 koi because contaminants from a grouting material around the edge of his pond leached in from surface water.

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The two types of waterfalls mentioned were "She" falls and "He" falls. A "She" fall bounces immediately over rocks and doesn't make as much sound. A "He" fall drops down to the surface of the water without interference and provides more noise, particularly if there is a recessed cavity behind the area of the fall which acts as an amplifier. A nice fall can be had by making it 1/3 "He" and 2/3 "She". Consider your neighbors when deciding which type of fall to install. A "He" fall can be quite loud at night when everyone is going to sleep and turning it off if you have fish in your pond can create low oxygen levels when they need it the most. If a pond is stocked with oxygenating bottom plants they actually demand more oxygen at night although they provide it during the daytime. In hot summer weather this can pose a danger to the fish if adequate aeration is not provided during the evening.

When constructing a course for a waterfall, the use of marine silicone under and around the rocks will fill in the empty spaces and force the water to course over the rocks where you can see it instead of disappearing underneath them! After figuring out the placement of your rocks, lift them off the liner and put down a layer of marine silicone. After installing the rocks, fill in between them with more silicone. (You can buy marine silicone at a hardware store.)

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More on Liners

Note: A 5' x 5' piece of liner is enough to line a whiskey barrel.

There were four liner samples provided at the seminar. One was underliner (fuzzy gray) to lay down on the prepared hole before installing the liner. It's also good to wrap around tree roots or large rocks that can't be removed. Then you can just install your pond liner over and around them. The sample that was green on one side is the next one mentioned. I can't remember the exact lifespan of it but think it was around 9 years. The solid black liner was the next best with a life expectancy of 20 years. The last sample which has underliner bonded to the back has a lifetime guarantee.


When stocking your pond with snails, be sure to get the Japanese Trap Door type. They will not eat the plants. Tadpoles are nice in the pond but keep in mind that when they grow up to be bullfrogs they will eat any fish that they can fit into their mouths.

When selecting fish for the pond it is recommended that you keep round-bodied fish with round-bodied fish and straight-bodied with straight. The straight bodied fish have different swimming habits than the slower round bodied and when frightened can dart around and injure the slower fish.

Deep water oxygenating plants such as Cabomba and Anacharis are good for the fish in your pond.

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Bio Filters

Without the aid of an illustration...a bio filter is a sloped watercourse with sections containing pea gravel. As the water proceeds downward, the impurities in it are captured and settle into the gravel. If you are going to build a bio filter is is suggested that the amount of water in your filtration system at any one time should be 5-10% of the total pond capacity... up to 1/3 of its total capacity.

Water Chemistry

I won't try to relate everything that was discussed about water chemistry. If problems come up, consulting a good reference would be in order. Here are the high spots:

Even though we are dealing with fresh water in our ponds, some salinity is necessary to soften the water and create a more hospitable environment for the fish. When adding fresh water or setting up the pond, the recommended dosage of sea ( additives) salt is 1/2 cup per 100 gallons. If you are adding water to your pond to replace evaporation, do not add more salt.

The carbon used in filters should be phosphate free. Avoid garden charcoal. Phosphates support algae bloom which you really want to discourage in your pond! Also look for macro porous charcoal...NOT micro porous.

UNPLANTED POND: During the first two weeks of a pond's life, its' ammonia levels will be the highest. Encourage the customer to TEST the water frequently. Treating the pH to maintain 7.0 or lower will help protect your fish when the ammonia levels are getting a bit high. Eventually ammonia eating bacteria will develop which will lower the levels of ammonia but raise the nitrite level of the water. The nitrites will become nitrates after that and nitrates are what feed the plants in the pond. Until this cycle comes full circle and achieves some sort of balance, it is important to TEST the water and manage the ammonia levels. Doing a water change every 3-4 weeks is a good idea. Change about 20% of the water (drain out 20% of old first) and be sure to add sea salt at the recommended rate for the amount of new water you've added. Changing more than 20% can shock the fish since not only are you lowering the ammonia levels but probably affecting the pH as well. Don't be tempted to change too much at a time.

PLANTED POND: Plants will consume the nitrates in the water so managing a planted pond is a bit different than when it has no plants. In a new pond the ecological balance has yet to be established so it's important to meet the nutritional needs of the plants until they can be supported by the pond's natural ecological balance. Use liquid food supplements at the recommended rate to feed the plants while waiting for the pond to produce enough of its' own nitrates.

Although carbons in your filtering system will remove organic waste and toxins, it will not affect the ammonia levels in your pond. Aquarium Pharmaceuticals has a product called Ammo Rocks which will absorb ammonia from the water. These are very light weight but will sink to the bottom and look like rock (must be where they got the name!).

If people want to discourage the growth of algae without the use of algaecides there are a few things they can do:

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Raccoons, Herons and Kingfishers can really take their toll on a pond if not checked. There are no foolproof methods, but the following ideas may help. For raccoons, removing the shelves on the sides of the pond discourages them from dining at your pool. They are not particularly interested in going swimming to catch their dinner. Also, you could try electrical deterrents such as a Fido Shock device. It isn't recommended that you use cement drainage pipe sections for your fish to hide in because fish will also hide when they are sick. If your fish is sick and hiding, he could infect your whole pond before you notice the problem and treat it. Providing other types of camouflage is good, however. Use rocks and plants in the bottom of your pond for this purpose.

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Miscellaneous Tips

The appetites of the fish in the pond will be affected by the water temperature. The fish go into a semi-dormant state in the winter when the water is below 50 degrees. During this time a good food to give them is a wheat germ preparation (follow label recommendations). This will usually be started in late winter-early spring. When the water gets over 50 degrees the fish will need regular food.

Become educated! Besides videos, good educational resources are books. Two that come highly recommended are Water Gardening (beautiful book, but I didn't catch the author/authors) and The Koi Encyclopedia. Sunset also has some good books on ponds and water gardening.

Mesh pots can be purchased for planting your water lilies. This allows the roots to have more contact with the water in the pond. Just line them with plain white paper towels (no dyes) before planting to keep the soil in until it settles. Our speaker also recommended putting the pump in a mesh pot along with rocks. This is nice for the pump but mainly keeps the consumer honest in the way he removes the pump from the pond for cleaning. Oil leaks in pumps usually occur because of a breakage in the cable where it attaches to the pump. This happens because of repeated lifting of the pump by its cord instead of reaching down and grabbing the pump itself (thus getting your arm wet!). If the contained pump is weighted by the basket, it must be lifted up properly. This really adds to the life of the pump.


Here are some great links for more information on ponds and water gardening:


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