Marginal Plants - Plants that thrive in consistently moist, boggy soil. e.g. Yellow Flag Iris, Cattail, Pickerelweed, Arum_Arrow.
Surface/Floating Plants - Waterplants with leaves that float on the surface, while roots trail below. e.g. Water Hyacinth
Deep Water - Lily
  Hardy (Perennial)
  Tropical (Annual)
Oxygenating Plants - these will be completely submerged in the water. e.g. anachris
  • Fertilize your plants with plant tabs at least monthly during the growing period.
  • Planting Medium:
    - Some sources say to NOT use garden soil or planter mix as a plant medium. se Use special aquatic compost, which is low in nutrients. Flourite and Onyx are specially fracted stable porous clay gravel for the natural planted. In a pinch use clumping kitty litter (unscented)aquarium.
    - Others say it is OK to use garden sub-soil. Do not add garden compost or fertiliser
  • 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
Some plants are sensitive to your weather conditions. See the zone for your location.


Goldfish: Comets, Shubunkins, ... are an easy way to start.
Koi: Are a little more expensive and complicated.

Recommended Mix
For each square yard of surface area:

  • oxygenating grasses (e.g. anachris) - 18" of depth 2 bunches, 24" of depth 4 bunches, 30" of depth 6 bunches)
    See: Aquatic Plant Prices at Hill Haven Greenhouse
  • 1 medium to large water lily
  • 12 water snails
  • 2 fish 4 - 5" (e.g. Golefish: Comets, Shubunkins Sarasas)


All ponds should have a nice coating of algae on the sides, rocks and bottom, indicating a healthy environment. This algae (slime) produces 60% of the oxygen in your pond and is one of the pond's stabilizing forces. Fish love it also.

Green water is prevalent during the first 90 days of pond balancing. The length of time depends on many variables such as weather, water chemistry, number of plants and fish, or the richness of your soil.
Your pond may also see a "GREEN" period in early spring, but this should be brief as long as your pond is balanced.
Although plants are a net producer of oxygen, at night they take up oxygen and give off carbon dioxide (CO2); Levels will usually not change significantly at night, but a severe algae bloom can deplete enough oxygen at night to kill fish. Increased CO2 can also reduce the pH of your pond.

Natural Control:
Algae needs sunlight, CO2 and nitrogen.
Add water lilies to reduce the amount of sun reaching the water. Free floating water Hyacinth are inexpensive and will also provide coverage. 50-65% coverage is recommended.
Add oxygenating plants to absorb carbon dioxide. They also produce oxygen during the day to help the fish breath.
Snails and fish eat algae.
Decaying debris on the bottom will produce nitrogen. Remove debris by skimming, siphoning, scooping, vacuuming (use a shop vac or pond vac) or whatever means are available.
A filter will remove most floating algae. Clean your filter every week or so.
However, it's not that simple. See: Green Water: Myths, Facts, Theories

See Artificial Algae Control below.

Color Condition Sympton or Cause
Dark Sparkling green Good
Dull green to yellow Not so Good Disolved Oxygen and pH are dropping.
Blue-green algae type becoming predominant.
Gray to black very bad Pond is septic. Anaerobic conditions prevail.
Tan to brown OK if brown algae However, brown algae can be a symptom of rising levels of Ammonia and Nitrites. Could also be caused by inflow of eroded soil.
Problem Solution
String algae S.A.B. and Barley Mats
Green water Supercharged AquaClearer bacteria & AquaAid Flocculant
Tea colored water Aquascapes activated carbon

Cloudy Water - Algae and other suspended solids

Algae Types
Free floating algae:
"green water" (e.g., Chlorella) algal blooms. Dense populations of suspended single-celled algae. A sub-category of Chlorophyta below.
Free floating "string algae" or "hair algae" (e.g., Cladophora). Can be beneficial in limited quantities.
Green Algea (Chlorophyta): Most commonly encountered; found everywhere. Occur as floating, attached, swimming forms and seasonal surface blooms.
Diatoms and Dinoflagellates (Bacillariophyta): Diatoms are a form of algae characterized by having cell walls made of silica. These are single celled, microscopic algae, ubiquitous, mostly beneficial in terms of nutrient cycling, oxygen production, competition with undesirable forms. Some commonly found diatoms are Asterionella, Fragilaria and Cyclotella.
Beard algae (Audouinella)
Blue-green algae (Cyanophyta) are composed of hundreds of types of which spirulina, aphanizomenon and microcystis are a few. They are now classified amongst the Bacteria, because they have no nucleus. Cyanobacteria is believed to be the first organism to start using photosynthesis for food production. The presence of this group is a danger sign in marine aquaria; usually something is seriously amiss filtration/circulation wise.
Stoneworts (Charophyta)
blanket weed (e.g., Oedogonium)
Golden-brown (Chrysophyta): Includes Synura, Uroglena.
Yellow-green algae (Xanthophyta).
Seaweeds are a kind of algae. There are three major groups:
  green (Chlorophyta) - Only about 10% of green algae are marine species, most live in freshwater.
  red algae (Rhodophyta) -
  brown algae (Phaeophyta) - This is the largest form of algae which exists as the seaweed kelp.
See:,,, Robyn's Pond Algae Page, Green Water: Myths, Facts, Theories,, Types of Algae, Freshwater Algae , algae
Robyn's Algae Information Page

at Van Ness Water Gardens
Artificial Algae Control:
Ultraviolet Clarifiers kill algae that is suspended in the water by exposing single-cell organisms to intense UV light in a device connected to an external filter pipe. In addition, disease bacteria, fungus, and virus cells are also killed. This doesn't affect algae growing on the sides of your pond.

UV rays strike bacteria, algae and protozoa breaking through the organism's outer membrane. The radiation reaches the DNA of the organisms, causing abrupt modification bringing about their destruction quickly and effectively.

At they say "Chemicals should never be used to control the growth of true algae in an aquarium, and should only be used in rare circumstances to control cyanobacteria. Correcting a severe algae problem requires time and patience. Natural methods of controlling algae are the best and most effective.

BI-AQUACULTURE is a proprietary blend of all natural biocultures and enzymes which digests/degrades extremely heavy concentrations of organic mass within an aquatic system, reducing nitrogen and phosphorus levels. Info at
Algicides (Pond Clear) can be used, but they are very rough on plants.

S.A.B. (String Algae Buster) It is fortified with dry bacteria and enzymes; It works by adjusting the micronutrients in the water of the pond resulting in conditions that are unfavorable for string algae. Useful in new ponds until favorable bacteria have time to colonize.

Uberkler, is very effective in eliminating the free-swimming (green water) algae.

Cutrine-Plus is used for filamentous types of algae.

Pond Care® AlgaeFix® [ poly(oxyethylene) (dimethylimino) ethylene (dimethylimino) ethylene dichloride] controls many types of algae including "green water" blooms and filamentous algae that cover the glass, ornaments, plants, and gravel.

Flocculents (clumping agents) (e.g. Aquarem, Crystal Lagoon) are much safer for fish plants and pets.
They are sprayed across the top of the pond, where they form a white cloud-like layer at the surface. This layer slowly sinks, catching suspended material and algae as it drops. (It's best to leave any pumps off during this part of the process.) The resulting layer of sludge can be removed by siphoning or filtering.
Crystal Lagoon is a poly electrolyte that uses a derivative of chitin that is a single chain polymer of immense molecular weight and dense electrical charges. The charges act as hooks, gathering up suspended material in the water to "flocs" or flakes that can be filtered.
Barley Straw - As the straw decomposes in the water, it releases peroxide which inhibits algal growth. See:

See: Water Care Products at, Van Ness Water Gardens

The average pond should maintain a PH of 7.5 to 9.5 with 9.5 giving the least amount of algae growth.

Pond Chemistry - Disolved chemicals - pH etc.


Nitrification uses bacteria in bio-filters to convert fish waste (mainly ammonia which is toxic) to nitrates. The nitrates will feed the plants, but you need a good volume of plants.

Ammonia is excreted by the fish gills as well as the normal food excrement. In a mature pond a class of bacteria in the biofilter removes the ammonia almost as soon as it is formed. The ammonia (NH3) is converted into other nitrogen chemicals called nitrites (NO2).

Another type of bacteria also present in the biofilter then converts the nitrites into nitrates (NO3), which is less polluting and toxic than either ammonia or nitrites - both of which are poisonous.

However, nitrates are fertilizer for plants and can lead to more algae.

See: Nitrogen Cycle


Aquarium safe Silicone Adhesive : I used stuff specifically sold for aquarium use. Others have had no problems using a general purpose silicone. The general purpose stuff is definitely cheaper, but you need to be sure you find stuff that does not have an "anti-mildew" agent like arsenic added to it. The anti-mildew agent is toxic to fish.

Winter Preperation

Remove as much organic waste as possible ( leaves, ect. ) from the pond bottom. Organic waste uses up valuable oxegen during decomposition. Change 1/3 of the pond water if necessary. add the appropriate amount of salt to aid slime coat regeneration of the fish and to help prevent parasites. Put a deicer in the pond. These units will kick on when the water starts to freeze and let the gases escape as well as oxygen enter. Cover the pond with a net to prevent leaves from being blown in and the predators from reaching your fish now that your plants are dying down and they have less opportunity to hide. The pumps should be removed from the pond and thoroughly cleaned. Oil filled pumps need to be stored in a bucket of pond or distilled water to prevent seals and gaskets from drying out. Magnetic and epoxy sealed pumps can be stored dry. See:
Old Garden Pond at MSN Groups

Other Chemical measurements

pH (acidity or alkalinity) sould be between 6.8 and 9

GH (General hardness) Rrefers to the dissolved concentration primarily of magnesium and other mineral ions.
A GH between 50-100 ppm is best

KH (Carbonate hardness) KH is basically the buffering capacity of your aquarium, a Kh above 80 ppm helps prevent sudden drops in ph.
Baking Soda (Sodium Bi-Carbonate HCO3-), is often used for KH.

pH - Alkalinity - Acidity

pH level between 6.8 to 8.5 are ideal for goldfish and koi.

pH can swing widely during the day, measuring from 6 to 10.
Carbon dioxide (CO2) dissolves in water to form carbonic acid which has a pH of less than 7 so pH will tend to fall when carbon dioxide is high.
Plants give off carbon dioxide and use oxygen during the night; the reverse is true during the day, as plants consume CO2 through photosynthesis.
Fish are always using oxygen and giving off CO2
Waste products decaying at the bottom of the pond give off CO2.
pH will be lowest in the early morning and highest in the late afternoon.
Large daily changes in pH can cause stress, poor growth and even death of the farmed animals.

Most aquatic organisms can live in a broad range of alkalinity concentrations. The desired total alkalinity level for most aquaculture species lies between 50-150 mg/L CaCO3

Rocks and cement (which contains limestone) will raise the pH of water. Some people paint rocks with something like Thompson's (r) Water Seal (r) Clear Multi-Surface Waterproofer to avoid

Reducing pH swings:
Aeration - Oxygen levels increase. Carbon dioxide is "blown" out of the water and this tends to push up pH levels.
Add Limestone or crushed oyster shell that they sell for chicken grit. Chemicals to adjust pH:
You should not change the pH one whole unit (e.g. from 8.0 to 7.0) in 24 hrs.
I had a pH test kit which only went to 7.6 and was trying to reduce it with one of the pH decrease solutions from the fish store. It said to put 5 ml for each 10 gallons. I had a 30 gal. tank so started with 15 ml = 1/2 oz. several times and it didn't seem to do anything, so I increased it to 1 oz. then 2 oz with nothing, so put in 4 oz. and it dropped all the way to 6.0. So you need something that will measure higher levels of pH, otherwise you can't tell what is happening.

Test your water hardness before trying to make pH adjustments. If a pH decreaser is added to hard water, it will decrease pH initially, but the pH may swing back dangerously in 24 hours because of the buffering capacity of hard water.
Don't change the pH more than 0.2 per day to avoid shocking the fish.

In addition to chemicals to raise or lower pH there are pH buffers to stabalize the swings.

Acid water (pH < 6.8 can be treated by adding agricultural limestone [CaCO3 and CaMg(CO3)2]. Agricultural limestone will not increase pH beyond a maximum of 8.3. The use of hydrated lime (CaOH2) or quick lime (CaO) is not recommended because either of these compounds can cause the pH to rise very rapidly, to levels that are harmful to aquatic life.

Alkaline water (pH > 8.5) can be treated in several ways:
"pH Down", a liquid sold in pond supply centers for $16/16 oz., claims to neutralize the materian which is causing the pH to rise.
Add White vinegar or muriatic acid.
2 oz of muriatic acid brought my 35 gal tank from 8.2 to 7.2.
Add Alum (Aluminum Sulfate [Al2(SO4)3])
Add Gypsum (calcium sulfate [CaSO4])
I did some testing:
Alum 4 lbs $8, Gypsum 5 lbs $5
1 1/4 cup of Alum in 2 gal of pond water at pH 9 lowered it to pH 5.
  The Alum added to water from the pond in a bucket remained clear.
  But when I emptied the 2 gal from the bucket into the 400 gal pond,   it caused the water to become very cloudy and lowered the pH to 6.5

1 1/4 cup of Gypsum in 2 gal of pond water at pH 9 lowered it to pH 7.
  The Gypsum left the water very brown.

See: Pond Management-Clearing Muddy Ponds - Adding Gypsum at Texas A & M
Koi Health & pH FAQs

See Also:
Uberkler Pond Setup Chart
Pond Maintenance
Pond Cleaning
Van Ness Water Gardens TJB Inc. Landscape Contractor

Algae Control at: Aqua Art, BI-AQUACULTURE
Alkalinity & Hardness In Ponds |

last updated 24 Feb 2012