Oxygen      Chemical set up     Water      Water Change     Plants      Fish

Oxygen                                                       

     Oxygen is essential for the well being of all life and that includes aquatic life.  Water adsorbs oxygen from any point where it contacts air.  For this reason a 10ft by 10ft pond having a surface area of 100 square feet will absorb oxygen from 100 square feet regardless of its depth and so the fish stocking capacity of a pond is relevant to this calculation.  Disturbing the surface with the use of air stones or turbulent filter returns such as venturis or waterfalls will increase the surface area because instead of a flat surface the ripples being made produce a wavy surface.  If you can imagine measuring a flat line that measures 10cm long ---------then compare this to measuring a wavy line ~~~~~~ also 10cm long the ups and downs increase it to maybe double the length.  If you try this with a piece of string you will see what I mean.

     Lack of oxygen will cause fish to gasp at the surface especially in the early morning.   Some unexplained fish deaths often at night when plant life is using up more oxygen than during the day are symptoms of lack of oxygen.  Larger fish which need more oxygen to survive along with fish such as orfe and rudd (surface swimmers) which are very sensitive to oxygen levels will normally be the first casualties.  Water can also develop an unpleasant smell and appear tainted.

     Improving oxygen levels is done by adding features such as waterfalls, air stones, squirting ornaments and venturis.  Reducing the load on your ponds system is done by ensuring, stocking levels are not too high, adequate filter size and maintenance, removal of excess algae and blanket weed and reducing the quantity of plants in the pond.  

     During warm weather especially humid weather caused by thunder storms it is vital too maintain adequate aeration.  This is because warm water contains less oxygen than cold water and humid weather also reduces oxygen levels.                            

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Chemical set up

     Pond water contains many different chemical elements, some naturally found within tap water, some from the waste products of fish, frogs and plants, and some from the mineral elements within the pond such as rocks and cement. This section concentrates on  waste products and how they are converted into safe products by a filter system creating a safe ecosystem for your pond. This is called the nitrogen cycle, nitrogen is a gas that makes up 80% of the air we breath and when it forms compounds with other chemicals it plays an important part of many living tissues.  

     Ammonia (NH3)  is the waste product excreted by fish and created by decaying plant life within the pond and it is toxic to fish. When passed through your pond filter along with the oxygenated water from the pond they flow through biological media which over a period of time has developed the beneficial bacteria which converts the ammonia into nitrites.

     Nitrites (NO2) are also toxic to fish, but other beneficial bacteria in the filter will convert these into less harmful nitrates. 

     Nitrates (NO3) are used by pond plants (including algae) as food, these nitrates will naturally convert into nitrogen.

     Nitrogen is the gas that makes up 80% of the air that we breath and that our pond needs to contain life.

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Water

Water adsorbs certain trace elements from many things that it contacts on its travels.  For example peat will soften water where as lime will harden it.  The hardness of water is generally measured in milligrams per litre (mg/l) of calcium carbonate (caco3).  Test kits are readily available from all good aquatic retailers.  If your households water is very soft then when you wash your hands soap will tend to lather up easily where as with hard water it will not.   Generally pond life prefer a moderate hardness level of around 200mg/l to 500mg/l.  

Water hardness is not normally a problem in ponds unless it is extremely high or extremely low.  Certain rocks, stones, and cement within your ponds edging will raise its water hardness. Water contact with items such as peat or rain will soften your water, and any of these will also affect its pH value                               

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Water Change

The water within your pond may appear to be clear and therefore presumably healthy, the fish may look healthy and the plants are growing well but the reality may be far different to what we can see with just our eyes. Far to often a pond will be built in a distant corner of the garden and therefore can be subject to neglect as it is out of sight and out of mind, especially during the winter months .

 To  ensure that your pond life has the conditions that are required for a healthy life you need to pay a little attention to the quality of the water, which after all, forms the boundaries of their world. It is often said that if you look after the water then the fish will look after themselves and ignoring hereditary diseases this is generally true.

You should be aware that pollutants which find their way into or naturally occur within a pond (such as Dust, Leaves, Grass clippings, bird and fish droppings) will rot and dissolve into the pond water.  When the water evaporates and the pond level drops the toxic pollutants do not evaporate and over time will reach dangerous levels even if water top ups are done regularly. 

For these reasons you should always add a good quality pond dechlorinator liquid to your pond when adding tap water and just topping up the level is not adequate as you should perform regular water changes (remove up to 25% of the ponds water and replace with treated tap water). Changing more than 25% may cause unnecessary stress on your livestock because it can cause large changes in the chemistry of the water such as the pH value.

 If possible try to avoid making water changes at the weekend as this is when the local water boards tend to automate the chlorinating process which can result in a higher level of chlorine than during the week when the process is monitored and regulated manually. 

     Check your pond water regularly for ammonia, nitrite, and pH etc, these are the first signs of an oncoming problem and are very simple and cheap to do with the easy to use test kits, which are readily available, at all good pond retailers. If these test kits show a problem you should perform a series of water changes until the levels have reduced to safe parameters                        

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Plants                              Back to Top

Floating Plants     Water Lilies  Oxygenating plants     Reeds   

With a little forethought and attention to detail your pond can easily be transformed into a beautiful and highly attractive feature, which can often become the main focal point of the garden.  The best way to achieve this is to plan in advance, so that when you arrive at your chosen nursery or water garden outlet you already know your needs and therefore can choose suitable plants for your pond without making unsuitable impulse choices.

 Consider your ponds weakest visual aspects and aim to improve them with good well-chosen plants Make a note of the available planting depths and avoid areas which will suffer from high flow or excessive splashing as plants (especially lilies) will not flourish in these conditions. Use aquatic baskets which have a very fine meshed sidewall, Modern baskets need no lining, but older baskets with larger holes in the sides will need a Hessian lining to contain the compost. It makes future maintenance much easier if you only plant using aquatic baskets.

Only use proper aquatic compost as other general composts contain chemicals, which will leach into the water and poison your pond life.  Any gravel or stones must be lime free and should be rinsed prior to use. Always give new plants a thorough rinse, to remove snail eggs and fairy moss etc, prior to introducing them into your pond. We recommend that you wear arm length rubber gloves when putting your hands into pond water so as to avoid infections, especially if you have cuts or know of a possible rat problem nearby.  

Large fish such as koi will naturally graze around the plants roots, loosening the compost and causing the plants to drift out from their baskets, destroying your planting.  You need to ensure that adequate protection is provided to avoid them being uprooted by covering the aquatic compost with an inch of washed aquatic gravel and topping with some large washed stones

 Plant maintenance is required twice per year to ensure an attractive feature.  Because the plants live in pond water, which has a constantly replenishing source of plant feeding nutrients, they can easily become overgrown and unsightly unless contained. 

Each autumn you should remove any dead or dying foliage so that it does not drop off and rot which would pollute the water and reeds should be cut down to around four inches above water level. If you have oxygenating plants, which have become overwhelming simple pull out any excess.

Then in the spring you should remove each basket and thin as necessary.  If the fine roots have penetrated the baskets sidewalls remove them by cutting them back to the basket with a normal but clean handsaw.  Any plants that have overgrown their basket need to be divided and re-potted.                             

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Oxygenating plants               

There are many different varieties of oxygenating plant such as ceratophyllum demersum (hornwort) and Ranunculus Peltatus (Crows Foot). Some oxygenators will need potting in small aquatic pots and should be placed below the water surface. Others need a small weight tied to them in order to keep them submersed.

If on a sunny day you look carefully at oxygenating plants within a pond it is possible to see tiny air bubbles floating up from their leaves, this is because they actually do produce oxygen during daylight hours but at night they do the opposite and use up oxygen.  Oxygenators adsorb a lot of the ponds pollutants, which are the plants source of nutrition, and as such they are a benefit to all ponds and help to use up nutrients required by algae reducing green water problems.

Fish will if hungry use these plants directly for feeding upon. If allowed to become too prolific within the pond, due to their rapid growth rate, they can cause fish to become entangled and die.

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Reeds

Reeds, Irises and other aquatic grasses are a good addition to any pond and in summer produce some beautiful flowers. They can easily be tied back, with fishing line, to the pond edge to stop them blowing over or being dislodged by large fish.

Some species can grow in excess of five feet tall so choose carefully when purchasing.

Maintenance is also easy as these plants can be simply divided and re-potted.

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Water Lilies

Quite simply the crowning glory in any pond, with amazingly beautiful flowers, and many different varieties readily available in many colours for all depths and sizes of pond. You can expect to see the first leaves reach the surface in late spring, followed by flowers in early-mid summer. Usually a flower will only last for a couple of days but new buds will replace them before the previous flower has died.

When potting lilies use an overlarge basket as the rhizomes (roots) grow fast and soon outgrow small baskets. Always pot with the buds upward and exposed, ensure that they have plenty of aquatic compost and a good layer of washed aquatic gravel on top. If your pond has large fish such as carp then you should place some washed cobbles onto the gravel to stop the fish rooting out the compost, in severe cases it may be necessary to wrap the entire pot in garden netting allowing a small hole for the plant to grow through.

 Large rhizomes can be split and re-potted into two baskets or the new buds can be cut from hard up against the base and potted to grow on.  Ensure that Lilies are planted at the correct depth for the variety (check the label) and avoid strong flows and splash from fountains etc.

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Fish

To work out the amount of fish for a pond you need know the surface area of the pond.

 To calculate the surface area is simply length x width = square surface area, for example a pond which is 10m long x 5m wide has a surface area of 50 square meters.  

When introducing fish into a new pond you should allow a maximum of  25cm of fish per square metre.

 Once a pond has matured (around three years) you can gradually double the stocking level to 50cm, never add large quantities of new fish at the same time and allow for the size that they will eventually grow to.

Only species, which can handle the temperature range of your region, should be put into your pond.

Do not put fish obtained from the wild into the pond, as these will most likely introduce unnecessary diseases (also do not dispose of unwanted fish into our natural waterways as this can have a devastating effect on the indigenous wildlife).

You should keep to the pond fish that you see at your local suppliers such as goldfish, comets, koi and orfe. Fish seen kept in glass aquariums are usually in there because they need warmer water and should not be put into your pond.

 Certain varieties of fancy goldfish (large wobbling ones for example) do not do well in a pond as they cannot compete against faster fish for food

When you first walk into a fish-retailing outlet your natural instinct should give you a feeling of   professionalism and experience, watch how other customers are being treated and advised.

Take a close look into the fish vats, do you see dead, sick or otherwise unhealthy fish. You may see, vats that are marked up as quarantine, but these are good because all fish should be quarantined before sale to the public.

All fish should be gently netted and placed into a clear plastic bag which should be 2/3 filled with oxygen injected from a cylinder into the bag and this bag should be placed into a darker bag so that the fish cannot see out. Larger fish should then be placed into a polystyrene box.

The main things to look for when choosing fish for your pond are signs of poor health.  A good healthy fish will have a healthy sheen to its body and will have good bright colours with gills that are blood red when viewed.  Avoid buying fish that have any one of the following faults.

Bent backs,   Split or missing fins,    Lose or Missing scales,   Cuts, abrasions or scars.   Ulcers and Sores, Wax like lumps,    Fungus on their skin      Cloudy or infected eyes.

Also avoid any fish that tend not to swim with the rest or hide on the base of the vat. If you are lucky enough to see the fish being fed, unhealthy fish will be slow at coming up for food.

How do I put my new fish in the pond

As soon as you get your new fish home remove the outer packaging and float the unopened plastic bag containing the fish in the pond for around twenty minutes, this allows the water within the bag to reach the same temperature as that of the pond water.

 Then open the bag and introduce an equal amount of the pond water into the bag, this is to let the fish get used to the different water chemistry of your pond (drastic changes in PH etc, could kill your new fish). Leave the fish in the bag for another five or ten minutes before releasing them into the pond, and if possible avoid introducing too much of the bags water into the pond.

 Do not feed for twenty-four hours after introducing new fish.

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