Oxygenating Plants
Because of their role in keeping down algae in the pond the oxygenators or submerged plants are the most important group to consider. You may not have room for other plants in a smalll pond but these should be a priority. They need a depth of 60-90cm (2-3ft) as any deeper and there will be insufficient light for them to survive, if the main body of the pond is too deep, raise them up or plant them on ledges, but do include them.
They produce oxygen during daylight hours and this is obviously beneficial to both the water chemistry and the fish.
They are leafy, soft plants and have small roots, depending on their leaves to absorb the nutrients that are dissolved in the water. As these are also needed by the algae, they are in direct competition for food and in this situation the oxygenators generally win, gradually starving out the algae. Oxygenators also provide cover for fish fry and other animal life, thus helping in their survival, especially from the adult fish which have cannabalistic tendancies.
Small water features such as troughs and sinks have a low water volume but at least one oxygenating plant is recommended, be aware though that they tend to grow rapidly and will need cutting back. In larger pools calculate the number of plants required by referring to the ponds surface area. Usually sold in bunches of unrooted stem cuttings, 5 bunches can be added for every 1 sq.m (10ft sq.) of surface area.
There are five or six main species of oxygenating plants normally available, and it is best to add a variety rather than stick to one species.
Fri, 06/25/2010 - 09:07 by Splashtastic
Tags: Autumnal starwort
Callitriche hermaphroditica (syn.C. autumnalis)
This submerged perennial has thin branching stems which can grow up to 50cm (20") long. The leaves are small, narrow and light green in colour, 3cm long and 1mm wide.
It is an excellent oxygenator and therefore makes a good hiding place for freshwater fleas, shrimps and newborn fish fry all of which need good supplies of oxygen.
It does not develop surface rosettes, unlike most starworts and grows mainly near the bottom of the pond.
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Spread indefinite
Water depth to 50cm (20")
Hardy
Full sun
Propagation by stem cuttings in spring or summer
Fri, 06/25/2010 - 09:07 by Splashtastic
Tags: Hornwort
Ceratophyllum demersum
The stems on this perennial are slender and often rootless, growing to 30- 60cm (1-2ft) long. They support whorls of dark green forked leaves 1-4cm in length, which can be quite brittle, they become denser close to the growing point..
This plant is shade tolerant and will therefore grow in deeper water than most submerged aquatic plants. It will also tolerate a wide range of water conditions and makes an excellent oxygenator for the pond and a refuge for fish fry.
Spread indefinite
Water depth to 60cm (2ft)
Hardy
Sun or shade
Propagation by stem cuttings in spring or early summer
Fri, 06/25/2010 - 09:06 by Splashtastic
Tags:
Water moss, willow moss
Fontinalis antipyretica
This aquatic moss is an evergreen perennial and has round or triangular branched stems. These can grow to 20-25cm (8-20") long and have olive green moss-like leaves, these grow directly from the stem and overlap each other like scales.
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Grow in shallow water in full light where the plants can be anchored to boulders to form a dense carpet and is a superb oxygenator. Excellent in moving water.
Height 8cm (3") Spread indefinite
Water depth to 45cm (18")
Hardy
Sun or shade
Propagation bunched cuttings
Fri, 06/25/2010 - 09:05 by Splashtastic
Tags: Water Violet
Hottonia palustris
A pretty perennieal oxygenator that has both attractive foliage and aerial flowers. Producing stolons (a shoot that bends to the ground or that grows horizontally above the ground and produces roots and shoots at the nodes) and erect stems, with whorls of light green leaves that are deeply divided, 2-13cm long and 6-10mm wide.
The pale lilac flowers which are 2-2.5cm across are borne on erect spikes 30-40cm (12-16") which emerge above the water in spring. The plant is not easy to establish and it performs best in shallow water in clear mud bottomed pools rather than being planted in baskets.
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Height 30-90cm (1-3ft)
Spread indefinite
Water depth to 45cm (18")
Hardy
Sun or shade
Propagation by stem cuttings in spring or summer
Fri, 06/25/2010 - 09:04 by Splashtastic
Tags: Curly Water Thyme, Curly Waterweed
lagarosiphon major
This semi-evergreen perennial has fragile branched stems which grow up to 1m (3ft) longand are covered with curling leaves 6-25mm long and 2-3mm wide.
It is widely used as an oxygenator and is one of the most common plants to be bought from aquatic centers, where it is often mis-labelled as Elodea crispa. Forming dense masses of submerged stems it needs to be cut back every autumn.
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Spread indefinite
Water depth to 90cm (3ft)
Hardy
Full sun
Propagation by cuttings at any time during the growing season
Fri, 06/25/2010 - 09:03 by Splashtastic
Tags: Milfoil, Parrot's Feather, Diamond Milfoil
Myriophyllum aquaticum (syn. M. brasillence, M. proserpinacoides)
A perennial that has spreading stems growing up to 90cm (2.9ft) long. The needle-like leaves are tightly packed, light green and arranged in whorls around the stem. The flowers are inconspicuous and yellowish in colour, they are borne on a spike that grows just above the water's surface in summer.
As well as being an excellent oxygenator the delicate leaves provide a hiding place for fish fry.
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An amphibious plant (able to live both on land and in water) it is usefull for softening the shallow edges of a pond and for hanging over the edges of troughs and barrels. It needs a minimum water temperature of 1 deg. C (34deg F).
Spread indefinite
Water depth to 45cm (18")
Half-hardy
Sun or shade
Propagation by stem cuttings in spring or summer
