While the UK basks in glorious sunshine with many people soaking up the good weather on the beach or in a swimming-pool, it is not all good news for many pets who rely on their owners to ensure their needs are attended to. A garden pond and its inhabitants are no different during this hot spell. Warm water becomes depleted of oxygen levels and this is can lead to fish fatalities.
A pond needs to absorb oxygen from the air but when the temperatures sore to around 90 degrees Fahrenheit, the oxygen saturation point is reduced leaving garden pond fish gasping at the surface for air. If you keep fish it is advisable to have some way of oxygenating the water.
How does oxygen enter the water of garden ponds?
There are two ways in which oxygen enters water – when rooted aquatic plants and algae undergo photosynthesis during the daytime, and as oxygen is transferred across the air-water interface. The amount of oxygen that can be held by the water depends on the three factors: water temperature, how much salt is present and pressure (the higher the altitude, the lower the oxygen absorption rate). Oxygen solubility increases with decreasing temperatures (therefore colder water holds more oxygen) and low salinity levels with fresh pond water holding more oxygen than salty sea water.
The water in a garden fish pond tends to be stagnant so water movement at the air-water interface is decreased versus that of flowing water in a stream so there is a smaller surface area available to absorb the oxygen. As a result there is less internal mixing so the upper layer of oxygen-rich water tends to stay at the surface, resulting in lower dissolved oxygen levels in the middle and bottom water layers of the fish pond.
Oxygen is lost from pond water when the temperature rises, when plants and fish breathe and when aerobic microorganisms decompose organic matter. Rooted aquatic plants and algae produce excess oxygen when they are photosynthesise, but during the night they use oxygen for life processes.
A pond should be able to function without the help from technology, but on hot days, an action plan needs to be put in place. Inserting a solar powered oxygen pond pump into the water will help to increase the oxygen levels to save your fish and the ecosystem of your garden pond. Pond plants and microbes need oxygen. They in turn help to keep pond water clean and free of algae.
Too many fish or too many pond plants can also disturb the equilibrium by further depleting oxygen levels during the summer months and therefor need to be dealt with. Aquatic submerged plants consume oxygen at night and therefor compete with fish for this life giving element. Too many fish will also further deplete the water of oxygen.
In addition, water levels will drop off in warm weather and/ or windy conditions due to evaporation so levels need to be topped up. If you have inserted a rubber pond liner such as Epalyn to seal your pond, the risk of UV damage is negligible as this material is resistant to adverse weather conditions. If you have a PVC liner you will need to be extra vigilant to avoid damage to the liner.
To order a solar powered pond oxygenator or pond liners, contact Liners Online or visit our website for further details and to place an order.
If you have other pets, they need their water bowls filled and birds do enjoy a splash in water too. Enjoy the lovely sunshine!