Water Gardening

Table of Contents

  1. Pond Construction
  2. Biological Requirements
  3. Calculating Volume
  4. Aquatic Plants
  5. Bog Plants
  6. Floating Plants
  7. Submerged Oxygenating Plants
  8. Moisture Tolerant Perennials
  9. Controlling Weeds & Pests
  10. Preparing Plants for Winter
  11. Happy and Healthy Fish
  12. Fish Predators and Diseases
  13. Caring for Your Pond with Products
  14. Seasonal Preparation and Care
  15. How to Clean Your Pond
  16. The Biological Filter

Pond Construction

  1. Determine the perfect location for your pond or waterfall.
  2. Mark out the dimensions and shape of your pond or waterfall with spray paint or hose.
  3. Dig down about 18" deep and 12" wide to make your highest shelf for plant life. Dig down another 18" x 12" to make the second shelf. Continue with this until you reach your desired depth. Make sure that all the shelves are level by laying a 2x4 across the pond. Do this for each shelf
  4. Spread a l" layer of sand over the entire pond including the shelves. This will prevent sharp objects from puncturing the liner.
  5. Determine the location and drop-off height of your waterfall.
  6. Using the soil that you dug out from the lower pond, build a wall of soil equal to the height of the waterfall to support it; you can also use cinder blocks for this.
  7. To determine the size of the liner you will need, take a tape measure and start on one side and measure down into the pond, across, and up the other side. This will be the width; add two feet for extra. Do the same thing for length but make sure to include the waterfall height and again, add two feet extra. (Note: This is only for the lower pond. The size of the upper pond cannot be determined until the waterfall is complete.) You will also need the same size under-layment.
  8. Installing under-layment. Do not trim until the pond is completed.  Pond
  9. Install liner. Be sure that it overlaps by at least 2 feet at the top of the pond. Fill it to the top with water to settle it and wait 1-2 days.  
  10. Pump out water. Start to build your waterfall with rocks until you are 4" below your desired height. 
  11. Determine the size and shape of your upper pond. It needs to be at least 2 feet deep. Install under-layment and liner. The liner to the top pond needs to overlap the liner coming up from the waterfall. This is in case of puncture from installing the waterfall rocks.
  12. Install the top rock for the waterfall to flow over.
  13. Place pump in the furthest location from the waterfall for proper circulation.
  14. Install oversized river round on the bottom of the lower pond and to surround pump and host to hide them. Pond River RoundFor shelves use wall stone to cover liner. This will give it a natural appearance. 
  15. Fill with water.
  16. To install bio-filter you will need a piece of PVC Pipe the width of the upper pond. Place a cap on each end. Cut pipe in half and install a T. Drill ½" holes spaced every inch on all sides.  Place in pond and connect.

Biological Requirements for Successful Water Gardening

Pond Size Lilies BOG Plants
Surface Plants Fish
3-4", 4-5"
Submersible Plants Snails (optional)
Highly Rec. 
XS 0-10SF 1 2 2 3 6 2
S 10-35SF 2 4 3 6 12 5
M 35-60SF 3 6 4 10 18 10
L 60-100SF 4 8 6 12 24 15
XL + 100SF 5 10 8 14 30 25

The approximate sizes of the ponds are based on surface measurements. Multiply the length at the longest point by the width at the widest point to obtain the surface square fee.

These figures are starting stocking requirements. More can be added as desired or necessary. Large and extra large ponds should be stocked with half of the above quantities initially and approximately two weeks later the balance can be added. The pond ecosystem will not be balanced if all the items are stocked at one time.

Note: These are approximate numbers and will vary from pond to pond depending on location and exposure.

Calculating the Volume of Your Pond

It is important to know the volume of water in your pond. Knowing the volume of water can help you determine the number of fish the pond can hold. Knowing the volume is important when calculating partial water changes and using pond maintenance and feeding products. The easiest method to calculate the volume of your pond is to measure the amount of water used to initially fill the pond.  Before you fill your pond for the first time, note the time it takes to fill a 5 gallon (18.9L) bucket with tap water at a constant flow rate from a garden hose. Then fill the pond at this same constant flow rate using the garden hose. Record the time (in seconds) it takes to fill the pond. Then, use the following formula to determine the volume of your pond.

Volume of pond =  Time required to fill pond (seconds) x volume of bucket gal/l) / Time required to fill bucket (seconds)

If the pond is already filled, the volume can be calculated by using one of the formulas below. Then convert the volume to gallons or liters.

Square and Rectangle Ponds
Length x Width x Average Depth = Volume (in feet or meters)

9'L x 6'W x 2'D = A pond volume of 108 cubic feet (3 cubic meters)

Round Ponds
Top diameter x Bottom diameter x Height (feet or meters) x .785 = Volume of Pond

(3'TD x 3'BD x 2'H) x .785 = A pond volume of 14.13 cubic feet (.39 cubic meters)

Converting Volume to Gallons/Liters
L x W x D x 7.5 = Gallons or L x W x D x 1000 = Liters

Back to Top

Aquatic Plants

Water Lilies

In garden pools, water lilies are usually grown in containers set in the pool. Hardy varieties should be planted in spring after all the ice is off the pond, but you do not need to wait for the last frost date. They may be transplanted as late as a month before the fall frost date. In Zone 5 (Northeastern Pa), for instance, hardy lilies may be planted as early as late April.

Tropicals should not be placed in your pool until the water has warmed to a steady 70° F at night. In colder water they will go dormant and be difficult to revive. Any water change should be made at least one week before the containers are placed in the pond. In Zone 10, which encompasses southern Florida and Texas, tropicals can survived winters outdoors. In all other zones where frost occurs, the cold kills tropical water lilies unless the tender tubers are stored in a greenhouse pool during the winter. Most gardeners simply treat tropical lilies as annuals, replacing them every year.

Position the water lily container on cinder blocks in the bottom of the pool so that the crown is between 6 and 18 inches below the waterline.  It will take several weeks for new growth to develop.  To speed growth, start by placing the container only 6 inches below the surface,  where the water is warm and lit by the sun.  Gradually lower the container to its final position as the lily pads grow.

Most water lilies need full sun from ten to twelve hours a day to bloom well. A few varieties, however, will bloom with only three or four hours of sunlight every day but the more sun they receive, the more flowers they will produce.

Water lilies need to be fertilized regularly. Tropical and hardy lilies should be fed one slow-release fertilizer tablet for every 8 quarts of soil every month during the growing season. Place a water lily plant fertilizer tab 3" into the soil and cover it. This way, the fertilizer will feed the water lily and not leach into the water adding algae growth. Then place a 1/2" small diameter gravel (1B Size) on top of the soil to prevent the soil in the container from clouding your pond water.

As water lilies grow, their outer leaves may turn yellow. This is normal. Simply remove the unsightly leaves and the water lily will produce new growth. Old blossoms may also be cut off.  In fall, after frost, remove the dead foliage from the pool.

As a precaution in winter, lower the containers of hardy lilies to the bottom of the pond before it ices over. If there is any risk of the pond freezing solid, remove the container before the ice becomes permanent.  Allow the soil to drain for a few minutes and trim away all foliage.  Wrap the container in moist burlap or peat moss and store at 40-50° F in a cool corner of the basement or garage.  Cover each container with a plastic garbage bag to keep in the moisture; check the soil regularly to be sure that it remains moist.

Bog Plants

In the natural living pond there are several different levels of moisture surrounding the area in and around the pond. The edges or "marginal" area that is too wet for regular grasses and dry land plants to grow; the area where there is water but it is not deep enough for the water plants (like the lilies); and last but not least the water area where the water is deep enough for lilies to root and grow. So, in reality we have two different "Bog" or "Marginal" areas to plant. Plants that grow in these wet areas are often referred to as bog plants or marginals.

Bog plants help provide shade, food, and oxygen for fish and other inhabitants of the garden pool. The plants also help to remove impurities from the water.

To over-winter Bog plants in a garden pond situation, the plants should be cut back in the late fall and the pots dropped to the bottom of the deepest part of the pool to keep them from freezing. If your pool is less than 18" deep and a thick ice formation is expected, remove the containers from the water and place them in a cool (40-50° F) area which is not subject to freezing. Maintain the soil in a damp, but not wet, condition throughout the whole winter. Keep and eye out for rodent damage. Bog plants can be placed in the pool after chanced of freezing are reduced and the temperature is increasing.

Back to Top

Creating an Environment for Bog Plants

Numerous woodland, marsh, and swamp plants flourish in boggy soil where their roots remain constantly moist. You can establish a bog at the edge of a garden pool, but if the two share the same water source, silt may move from the boggy are into the pond, so it is best to separate the pool from the bog with a natural sill of garden soil or with a paved walk. Create an artificial bog by underlying the garden site with PVC or 500-gauge plastic sheeting to keep the soil wet. Excavate the bog garden to a depth of 9" and spread the sheeting across the bottom and 6" up the sides.

Though you should take reasonable precautions to prevent punctures by removing large sticks and rubble, you needn't worry about creating a perfect seal. In the bottom of the liner, scatter a layer of medium-sized pebbles to a depth of approximately 2". This under layer allows surface water to drain to the catch-sheet below. Before you return the topsoil, enrich it with well rotted manure, garden compost, or moistened peat moss.

The amount of watering required varies according to the weather. Try to keep the soil constantly moist by watering regularly during dry spells. Most bog plants are tough and will survive a few dry spells without extra watering though they may not look their best.

Floating Plants

All this group have in common is their ability to feed through roots suspended in water without any contact with soil. They vary greatly in form, character, and ornamental value. By shading the water and using up nutrients they can help in suppressing algae, and fish use the root masses of some as spawning mats.

Eichhornia Crassipes (Water Hyacinth) - Has swollen leaf stems that make each plant a buoyant island of dark shiny green. It raises spikes of beautiful pale lavender flowers and trails and has lengthy root masses ideal for spawning fish. The showiest of the floaters in a favorable climate, it can spread at such a prodigious rate as to become a serious nuisance. It is safe outdoors only in the summer.

Pistia Stratiotes (Water Lettuce) - Really does resemble a flat type of garden lettuce but with leaves of felt. It needs warm summer temperatures.

Submerged Oxygenating Plants

These are the plants that are commonly referred to in the United States as oxygenating grasses. In Britain they are called water weeds more often that not, which is a poor reward for what are, in effect, the pond's valuable maids-of-all-work. They provide a spawning medium for fish and a hiding place for fry; they harbor astonishing numbers of food organisms and, in addition, are themselves a valuable part of a goldfish's diet. They also produce oxygen, of course. So do all the other plants in the pond, those with leaves on or above the surface discharge it into the air; oxygenators release it directly into the water (only, however, under the influence of strong light). At night they produce not oxygen but carbon dioxide, and, since fish are using oxygen and producing carbon dioxide all the time, it is clear that the notion of so many oxygenators plus so many inches of fish producing a balanced oxygen/carbon dioxide exchange is a fallacy. In fact, in a pond with the sort of proportions that have been discussed, all the oxygen fish need will be supplied simply by the natural process of absorption through the water surface.

What makes oxygenating plants valuable is not the production of oxygen; that is, possibly, the least of their virtues. Oxygenators need nutrients to build up their rapid summer growth and they feed not through roots, which are primarily for anchorage, but by absorbing dissolved mineral salts directly from the water through their leaves and stems. In this they compete directly with algae which rely on the same food source. The algae, starved of light by the leaves of water lilies and starved of food by the competition of oxygenators, need to be present in some numbers from the beginning in a new pond filled with mineral rich tap water even further enriched by minerals dissolving out of the soil in planting containers. The standard recommendation is one bunch for every 2 square feet of water surface area. I would be satisfied with one for every 3 square feet in pools up to 100 square feet; above that one for every 4 sq ft until, beyond 500 sq ft, I would reduce the rate to one for every 6 sq ft.

It is often stated, by people who should know better, that oxygenators are "just dropped in". True, some of the drifting fragments will eventually root somewhere, but this is not the way to get growth going quickly. They need to be planted.

Cabomba - Feathery green and purple leaves on dark stems

Elodea (Anacharis) - Whirls of deep green leaves. One of the better oxygenation grasses.

Back to Top

Moisture Tolerant Perennials

(Can be planted along the edges of your pond)
  • Arenaria Montana (Mountain Sandwort) - White flowers in early summer.
  • Aruncus (Goatsbear) - White flowers in June & July.
  • Astilbe (False Spirea) - Assorted colors and bloom periods and well as heights.
  • Boltonia Asteriodes (White Boltina) - August bloom.
  • Campanula (Bellflower) - Assorted bloom color and heights.
  • Chelon Lyonii (Turtlehead) - Pink August bloom.
  • Coreopsis Rosea (Rose Coreopsis) - Pink bloom June to frost.
  • Digtails (Foxglove) - Assorted colors.  July and August bloom.
  • Eupatorium (Boneset) - Pink bloom July to September.
  • Ferns
  • Geranium Sanquineum (Blood-red Cranesbill) - Assorted colors June to frost.
  • Helenium (Sneezed Weed) - Yellow July to September.
  • Hemerocallis (Daylily) - Assorted colors, bloom periods, and heights.
  • Hosta - Plantain, leafy perennial.
  • Iris:
    • Yellow - Pseudacorus - June
    • Blue - Sibirica Caesar's Brother - June
    • Gold - Blk - Sibirica Ruffled Velvet - June
    Liatris (Gay Feather)- Purple or white July to August..
  • LiriopeLiriope (Lily Turf)) - Grassy-like ground cover.- Grassy-like ground cover.
  • Lysimachia - Yellow blooms in July.
  • Lythrum (Loosetrife) - Pink or violet July to September.
  • Monarda (Wild Bergamot))- Assorted colors July, August, and September.- Assorted colors July, August, and September.
  • Physostergia Virginiana (Obedience)- Pink or white in August and September..
  • Polemonium(Jacob's Ladder))- Blue in July and August..
  • Polygonatum((Soloman'sSeal))- Very fern-like..
  • Pulmonaria(Lungwort))- Red in May and June..

Controlling Aquatic Weeds and Pests

In garden pools, floating and submerged plants often grow so abundantly that they must be thinned out to keep some water surface open. You can pull excess plants out by hand or with a plastic garden rake. If you keep an eye on these plants and do not let them get out of control, your weeding task will require only a few minutes a week.

A number of insects (fewer than those found elsewhere) are fond of eating aquatic plants. With close observation you will be able to spot the pest. You can pick off caterpillars by hand; wade into the pool wearing wading boots to reach plant, if necessary. Other small pests can be washed away by pushing the leaves underwater or spraying with a stream from a hose.

Most insecticides shouldn't be used near the water, since they can harm fish. BT (Bacillus thuringiensis), a bacteria pathogenic to young larvae, is safe to use on all caterpillars and worms. This is available under many brand names; follow directions on the label. Some water gardeners use a vegetable oil on aquatic plants to smother insects. The most common pests troubling aquatic plants are described below:

China Mark Moths

Large oval holes, cut marks, cutting or shredding in the foliage of aquatic plants, especially water lilies, are signs of the China Mark Moth caterpillars. There are two kinds of the China Mark Moth. The caterpillars feed on the under and upper sides of the leaves and bind cut pieces of leaves around themselves with silk. They also bore into leaf stems, killing the leaves. Damage inflicted by these pests is unsightly but not serious enough to kill the plants. Caterpillars can easily be picked off by hand or controlled with BT if you catch them while they are still small.

False Leaf-Mining Midge

A narrow tracery of lines appearing on the upper surface of a water lily foliage is a sign of False Leaf-Mining Midges. The midges lay eggs in the foliage and the larvae form mines or tunnels in the leaves. Pick off infested leaves and destroy them to prevent the pest from spreading.

Water Lily Aphid

The Water Lily Aphid is especially prevalent during warm, humid weather, when it attacks leaves and flowers. The small wingless insects reproduce prolifically, causing disfigured growth and spreading virus diseases. To control them, hose foliage with water. If any are left behind, submerge infected flowers and pads and shake them underwater to remove the pests. An active fish population will take care of the ones that are dislodged. In severe infections, some gardeners spray with a mixture of corn oil and water. The oil should smother the pest without harming the fish. Do not spray new leaves when the temperature is over 80° F.

Back to Top

Preparing Plants for Winter

Water lilies can be permitted to die down naturally. Leaves and flowers should be cut off as they die back and turn brown. The less debris left to decay in the water the better. They (lilies) can be left in the pool as long as there is at least 9-10" of water covering the top of the pot. If there is less than this it is a good idea to pull the potted lily up after dormancy has set in and place it in a 5 gallon bucket to be stored in a place that is cold yet a hard freeze will not occur (perhaps a garage).

Oxygenators should be cut back and left at the bottom of the pool. Excess should be removed.

Bog Plants should be cut back after the first hard frost and sunk to the bottom of the pool. They should be raised as soon as the temperature starts to rise.

Hardy Floating Plants produce turions (winter buds) which fall to the bottom of the pool to reappear the following spring when the water warms up. In the autumn, before these buds disappear, you can collect a few and store them in a jar of pool water with a handful of mud on the bottom. Keep them in a cool, light place until spring when they can be encouraged into early growth and put in the pool to help keep down early algae growth.

The How and Why of Happy and Healthy Fish

Most pool varieties of the hardier gold fish (Commons, Commets, Fantails, Shubunkins) as well as Koi, winter well in an outdoor pool as long as the pool doesn't freeze completely to the bottom and there is a small open surface area for gas exchange. As water turns colder the fish activity comes to an almost complete standstill. By the time the pool is beginning to freeze over the fish are just hovering, almost motionless. They have gone into a type of hibernation and since they are not exerting any energy they will need NO FOOD.

In Spring, as water temperatures begin to rise, you may gradually begin to feed again. BUT BE CAREFUL!!! Fish can, at this time, overeat, bloat and die. So feed sparingly until the return activity levels. This whole process is dependent upon water temperature. Don't change pool water often. In a well balanced outdoor pool, once a year is enough. Change it in the spring when the pool is drained to split and repot water lilies and bog plants that have outgrown their pots or you can change the water in the fall when you are cleaning the garden pool and cutting back the vegetation. Leaves and other organic matter should be removed from the pool in the fall to eliminate the toxic (to fish) gas which is released as they decay. One of the best reasons for doing the water change in the fall is that the fish are not at their peak and the stress of cleaning the pool and adding fresh water will not be as great. When changing the pool water, transfer the fish into a container of the pond water from which they were taken and set them in a shaded place. Refill the pool with a hose set on spray, since this will help to dissipate the chlorine and incorporate oxygen. If you don't have time to let the chlorine dissipate you can used a product called Contrchlor or Aqua Safe. When pool water levels drop due to evaporation, try to add water when the drop is around 2" thus you avoid adding to much "fresh" water at one time but always spray it in.

In an outdoor garden pool, fish will do well in whatever temperature the season may bring. Occasionally fish will become ill. But, when they do, owners must react quickly to control the problem. It is helpful to realize that all fish carry pathogens which do not cause problems until the fish are placed under stress.  Since summer brings about the combination of two stress factors - heat and increased oxygen consumption - you may want to treat your fish at this time with DesaFin. ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS EXPLICITLY.

DesaFin can also be used when adding new fish to the pool. To find out how many fish you can safely add to your pool, keep in mind the goldfish rule: "Buy 1" of fish (don't count the tail) for every 20 square inches of water surface area". When introducing new fish to the pool, place the bag in the water 10 to 15 minutes to allow water temperatures to equalize. If it is sunny and hot, shade the bag with a piece of newspaper to avoid the greenhouse effect of the plastic bag. Then, after the water temperatures have equalized, slowly add the fish to your pond.

Feeding the fish in your pond will be one of your favorite things to do. Feed fish once a day and feed only what the fish can eat in 5 minutes. If you use this rule you will have very little water settling to the bottom of your pool which will cloud the water. If you can't be there to feed every day, it is no hardship for the fish because they can go 4 to 5 days without supplemental food. Don't forget that in the natural world Mother Nature provides food in the form of insects and plant materials for the fish to eat.

Fish Predators and Diseases

Two types of beetles occasionally attack and kill fish in garden ponds. The great diving beetle measures about 1½" long and ¾" wide. It's body is dark brown and tinged brownish gold. The beetle attaches itself to the body of a fish and feeds off its juices. Since they must surface periodically to breathe, you can net the pests with a hand net and destroy them.

Water boatmen beetles swim on their backs on the surface, using their legs like oars to speed themselves across the water. They can inflict wounds on large fish and kill the fry. Frequent netting is the only way to dispose of these pests.

Fish diseases may be caused by bacteria, fungi, or parasites and can kill fish if they are not treated. Often, overstocking or dirty water causes the fish to weaken, which leads to disease. Fish under stress are particularly susceptible to disease. Stress may be caused by transportation, low oxygen supply, high ammonia content in water, improper water pH, sudden temperature or pH change, and improper diet.

Disease symptoms are not difficult for a beginner to observe. If you see a fish that is blotched or discolored, remove it immediately. A number of general fish medicines are available for parasite, fungus, and bacterial control. You may want to keep these on hand. Consult a book or local fish dealer for help in choosing the correct treatment.

If there are too many fish in the pond waste builds up in the form of ammonia, which leads to gradual poisoning. Gases given off by excessive leaf decay can also cause fish to weaken and die. The best remedy in either case is to remove the fish, change the water, and reduce the population before returning the healthy fish to the fresh pond water.

Most of the routine care needed for your water garden won't take much of your time. As you're enjoying the pool, you'll clip a dead blossom here, a pad there, add a bit of water from the garden hose, and wash off a few pests at the same time. Part of the enjoyment of you pool comes from the involvement you feel in tending to it...and that comes naturally.

Caring for Your Pond with Pond Care Products

If your pond has been dormant from the winter cold, then spring is a good time to clean and inspect the pond. Begin with AMMONIA REMOVER to absorb excess ammonia that will build up as water warms. This will also give the biological filter a chance to resume normal activity. Ammonia levels should be tested weekly. Make a 15% to 25% water change over several consecutive days to eliminate elements that may be polluting the water.  Use CHLORINE AND HEAVY METAL NEUTRALIZER when making a pond water change. It will safely remove the toxic chlorine and heavy metals in the tap water.

To remove the buildup of sludge that has accumulated on the pond floor or rocks, treat the pond with POND-ZYME. The digestive enzymes quickly break down pond sludge. A buildup of sludge can result in low PH and oxygen levels.

After a long cold winter, pond fish are especially susceptible to disease. Use STRESS COAT to restore the natural slime coating that helps fight off fish disease. The protective coating of Aloe Vera will also promote healing of skin wounds.

As pond water temperature gradually rises to 50°F (10°C), pond life becomes more active. Begin feeding pond fish lightly for the first two weeks into the season.  SIGNAL FEEDER BLOCKS can be used as a first food of the season. Fish can feed at will as the block begins to slowly dissolve in the pond. The food is available to the fish continuously. When the block has dissolved and the food has been consumed, a brightly colored float will bob to the surface, signaling that it's time for a new block.

At the same time, pond plants begin seasonal growth. To help promote flowering, use AQUATIC PLANT STIMULANT to supply important elements to stimulate healthy growth of all pond plants. AQUATIC PLANT STIMULANT does not add phosphate or nitrate, therefore it will not cause algae blooms.

In late spring, many ponds experience a temporary algae or bacterial bloom caused by sunlight, buildup of dissolved organics, phosphates, and nitrates. These blooms will clear up in time, but until then the pond water will appear cloudy. Immediately use ACCU-CLEAR to quickly clear cloudy pond water. It clumps the tiny suspended dirt and debris together, allowing it to be filtered out of the pond water.

Back to Top

Seasonal Preparation and Care


As water warms, everything becomes active. Use ACCU-CLEAR to reduce "green water". Add PHOSPHATE REMOVER to control the nutrients that cause the algae blooms. Pond fish and aquatic plants are most active during the summer months. The SIGNAL FEEDER BLOCKS can be used weekly or when you're on vacation as a supplement to regular feeding. AQUATIC PLANT STIMULANT helps both flowering and oxygenating plants in the pond. During summer, the pond is most susceptible to algae blooms. The health of pond plants is important because plants use the nutrients responsible for algae blooms.

Excess fish foods and decomposing plant matter can cause dangerous ammonia and nitrite to appear in the pond. Acid rain can cause lowering of ph, disrupting the proper biological balance in the pond. Test the water regularly with DRY-TAB test kits to monitor water conditions. POND-ZYME should be used throughout the summer to break down fish waste, dead plants, and algae. The need for water changes may become more frequent. Use CHLORINE AND HEAVY METAL NEUTRALIZER when adding water. Add STRESS COAT to prevent diseases and to condition fish skin.

During the hot summer days, even the cleanest pond can experience low oxygen conditions. Make sure fountains, waterfalls, or aerators are working especially well during hot weather to ensure proper oxygen levels.


We suggest the use of a Mesh Net cover to keep leaves out of the pool.  Fall is the season to prepare the pond for winter. Reduce fish feeding gradually. When water temperature drops below 50°F (10°C) discontinue feeding fish and aquatic plants will become dormant, waiting for spring to bloom again.  Remove fallen leaves and debris from the pond before they settle to the bottom. Make a 15% to 25% water change over several consecutive days.  Add a final dose of POND-ZYME to reduce sludge buildup.


In the early part of Fall (late August to mid September) it's time to start preparing your pool for Winter. When you notice a slackening plant growth and a slight drop in temperature it's time to cut back the oxygenators (hard). They are not needed as much as the weather begins to cool. If it's at all possible, remove all the old flower blooms and leaves from the water lilies as they brown. Cut back all marginals (bog plants) after the first frost hits them and turns them to an ugly brown. Try to keep as many of the falling leaves and debris out of the pond to eliminate falling leaves from trees and shrubs entering the pool. THE WHOLE THING IN A NUTSHELL IS TO KEEP AS MUCH ORGANIC MATTER OUT OF THE POOL AS POSSIBLE.   WHEN WINTER COMES AND THESE THINGS DECOMPOSE, TOXIC LEVELS OF METHANE AND HYDROGEN SULFIDE MAY DEVELOP!!

If a covering of ice coats the pool for even just a few days, the natural gas exchange through the water surfaces is cut off and the fish can suffocate. To open a hole in the ice, place a bowl of boiling water on the surface and allow it to melt its way through; adding fresh boiling water as needed.  To help maintain an opening, a small immersion heating unit (pool heater) can be used when threats of a real freeze occur. If there is no power source for a heater the best thing to do is to cover the end or corner of the pool with polyethylene. If the pool is a small one, completely covering it for severe weather is a practical way to go and a clear sheeting should be used to allow light penetration.

Hitting the surface of a frozen pool to make a hole is not a good idea. The pounding creates shock waves which can kill the fish. Also, the stress created by pounding on the ice can cause fractures to fiberglass pools and punctures to the liner can also occur. To avoid stress on liners, fiberglass inserts, or concrete, floating of compressible objects which will absorb the pressures and take the strain off the walls is a help. Planks or logs are ideal. Polystyrene boxes which are ballasted with stone to prevent them from floating too high in the water are also good.

How to Clean Your Pond

Cleaning your pool in the Fall or early Spring when temperatures are 45 to 70°F is recommended. Avoid cleaning your pool during the summer (unless it is necessary due to foul water or chemicals accidentally spilled into the pool) since the fish will stress easily at this time of year.

Items needed:

  • Holding tank for fish
  • Stiff brush
  • Pump and tubing or hose
  • Bucket
  •  Fish Net
  • Netting or boards to cover holding tank
  • Medifin
  • Dechlor or Aquasafe
  • Measuring spoons
  • Extension cords if necessary (UL outdoor approved)


  1. Set up holding tank for fish in a shaded area. Clean plastic trash cans, tubs, or wading pools are suitable. If possible, provide aeration.
  2. Fill holding tank with original pool water.
  3. Remove fish, snails, tadpoles, etc. to holding tank and cover with netting or board.
  4. Pump remaining water out of the pool.
  5. Remove plants and cover with wet newspaper. Place them in a shaded area.
  6. Bail out any remaining water.
  7. Scrub the pool floor with a stiff brush and clean water. Do not remove any beneficial algae from the walls of the pool.
  8. Rinse and drain.
  9. Fill pool.
  10. Add Dechlor or Aquasafe according to label directions.
  11. Add Medifin according to label directions to eliminate any potential parasite problems.
  12. Reintroduce fish by adding the new, treated pond water to the holding tank so that the water temperature in the holding tank is within 3°F of the pond water.  Replace fish into the pool.
  13. Repot plants if necessary and put them back into the pool.
  14. If applicable, clean filter.

The Biological Filter

A biological filter is an important part of the ecosystem in any pond. It provides the bacteria necessary to remove the harmful pollutants in pond water. The biological filter comprises two species of nitrifying bacteria, nitrosomonas, and nitrobacter. The nitrosomonas species convert poisonous ammonia into nitrite, which is relatively non-toxic and is used as a nitrogen food source by aquatic plants. This continuous process is called the NITROGEN CYCLE.

When stocking a pond, add only two fish to the pond each week. This allows the biological filter time to grow and to detoxify the ammonia and nitrite. Use the DRY-TAB MASTER TEST KIT FOR PONDS to monitor ammonia and nitrite levels every 3 days during the first 4 weeks of initial setup. If ammonia or nitrite is present, reduce feeding and do not add fish. Make small water changes daily (10%). Use AMMON-ROCKS or AMMONIA REMOVER to naturally remove ammonia before it reaches toxic levels or is converted to nitrite. Remember, there is plenty of time to add fish to the pond.

Good luck and don't forget to sit back and enjoy your water garden!