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Why EVERY Garden Fish Pond Needs a Good Reliable Pond Pump

A lady rang this morning to discuss a problem with her goldfish; about 10 fish out of 30 had died over a period of days and more were appearing sick. 3 of the fish were swimming with difficulty, were bloated and also had scales apparently coming away from their body. This suggested that the goldfish were infected with a bacterial disease called dropsy. This article is not about Dropsy (also called pine cone disease) but about pumps and oxygen in water because it came out in the conversation that she did not run her pond pump 24/7.

Dropsy is a serious, and usually lethal condition brought on by stress inducing factors like sudden water temperature changes and poor water quality caused by build up of ammonia and other toxic chemicals as well as a lack of dissolved oxygen in the pond water. Expert advice should be sought but recovery from true Dropsy is highly unlikely.

Why Your garden Fish Pond is a Potential Death Trap ... because there are always too many fish in the pond.

If you have a fish pond as distinct from a pond with just plants it is vital that a suitable submersible pump is installed. The reason for the pump is mainly to circulate water through the pond biofilter ... it is not to just simply circulate water. Here's why ...

Fish confined to ponds live in an overstocked unnatural environment. Because the fish density in almost all fish ponds is very high per cubic metre of water things are too crowded and to ensure goldfish or koi survival it is important that the pond water is continuously purified.

In nature this purification process is the result of naturally occurring bacteria that reside on the bottom of the pond, on rocks, sunken trees and in fact any underwater structure.

The water in a lake is continuously circulated by the action of wind and the waves allow fairly high concentrations of oxygen to become dissolved in the surface layer and this oxygen rich layer is then mixed and distributed through the body of water by movement of the large water mass.

Bacteria in the lake utilise this dissolved oxygen in the process of converting fish waste to non toxic chemicals much as the bacteria in a sewage plant does a similar job.

These oxidising bacteria need large amounts of oxygen to do their job and they get it from that oxygen dissolved in the lake water. It is this oxygen and low fish concentrations (therefore low quantities of waste products ... mainly ammonia) that allow lakes to establish themselves and remain viable over long periods of time.

In a pond the action of wind is negligible and the fish if left without a means of replenishing oxygen or a man-made pond purification system would struggle to survive. The name we give to the artificial garden pond purification operation is biofiltration and the process consists of converting fish waste (ammonia) into nitrates that act as plant fertilizers. In this way in a well balanced pond system nitrogen levels are kept reasonably constant and the danger of fish dying from ammonia poisoning is reduced dramatically. However with no pond biofilter or an inefficient one ammonia would build up, fish would become stressed and therefore prone to disease especially in springtime. In the worst case scenario levels of ammonia would reach poisonous levels and the fish would die ... just as some goldfish in a bowl may die after about 7 days.

Your Garden Pond Filter Will NOT Work Without A Continuous Supply Of Oxygen And This Is Why You Need A Pump

To ensure that the bacteria in the biofilter remain alive and do the job of consuming ammonia they must be supplied with water containing dissolved oxygen on a continuous basis ... this means 24 hours per day 365 days per year. In turn this means you have to PUMP water through the biofilter 24/7. If you stop the pump for even a few hours the water left behind in the filter will give up all its oxygen to the "gasping" bacteria until there is no more left and all the bacteria will suffocate. Once the bacterial colonies which exist in extremely large number are dead it takes weeks to build  a viable population again.

In summary overpopulated fish ponds will suffer from diseases and fish deaths if the water is not continuously purified using a pond filter and if the pond biofilter is not kept alive with continuously flowing water.

Oxygen is replenished in a pond using waterfalls and fountain arrangements (those that spray into the air and cascade back onto the pond surface with a splash ... the splash from the fountain increases oxygen transfer from air to water considerably).

Other articles on this web site will show you how to select the right pond pump for your individual situation and also how to choose the right pond filter for your pond. Choosing the right pump products requires a knowledge of waterfall pumps and/or fountain pumps and by making the right choice you can save not only a lot of money but get peace of mind too that your fish are well cared for in their aquatic or watery home.


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