Biological Garden Pond Filters Require Plenty of Oxygen
Why Does My Pond Bio Filter Need Oxygen?
Just like humans need oxygen to breathe your garden pond requires a plentiful supply of fresh oxygenated water in order to remain a healthy environment for Koi, goldfish and aquatic pond life to thrive.
Atmospheric air is approximately 21% oxygen. This oxygen is readily absorbed into your pond water where it is rapidly used up by aquatic pond life and the biological processes taking place in your biological pond filter.
Oxygen is not only needed by your pond fish to live but just as importantly it is needed by the beneficial bacteria Nitrosomonas and Nitrobacter that colonize the pond filter media and by aquatic plants at night time when they revert from producing oxygen using a process known as photosynthesis into using up valuable oxygen.
A garden pond can never have too much oxygen circulating around.
Gerry Preston, a writer for Nishikigoi International, a specialized Koi keepers and breeders magazine states that garden ponds should only contain 3 things: fish, water and oxygen.
I would recommend that in addition to your pond pump that circulates water to add another means of aerating the water. Popular methods include adding a waterfall or using a pond air pump
The amount of oxygen in your garden pond is influenced to a large extent by the outside temperature and the temperature of the pond water. During summer it becomes increasingly difficult for oxygen to be absorbed into water. This is mainly due to lack of surface movement.
The opposite is true in that oxygen levels within a garden pond environment will be at their highest during a cold, windy winter’s day. Cold water has a far better ability to hold oxygen than warm water and there will be more surface movement, making it easier for water to be absorbed into the pond.
As stated earlier in this article oxygen is used by nitrifying bacteria Nitrosomonas and Nitrobacter that colonize pond filter media. These beneficial bacteria are responsible for converting toxic ammonia, produced by fish feeding, decaying or rotting organic matter and uneaten fish food. Without the presence of these beneficial bacteria colonies in your pond filter you simply would not be able to maintain a garden pond with live fish. Ammonia is extremely poisonous to aquatic pond life when the concentration is high.
Unlike natural lakes and ponds where there is a high volume of water and relatively small amounts of fish in comparison to the size, a garden pond has a high fish load compared with the total volume of water within it. The level of ammonia in a natural lake or pond is relatively low for the reasons outlined above. Unfortunately in a garden pond the opposite is true. It is critically important to control the amount of ammonia, present within a pond system.
The chemical processes involved in converting ammonia by Nitrosomonas and Nitrobacter beneficial bacteria consume vast amounts of oxygen. Without oxygen, as is the case with humans these beneficial bacteria will die. The oxygen is contained in the water being pumped through the pond filter by your pond pump. You should never switch your pond pump off for long periods of time if you can help it as it only takes about 5 to 6 hours without oxygen for the nitrifying bacteria in your pond filter to be totally wiped out. Once the bacteria have been wiped out the level of ammonia rapidly rises, particularly if you continue to feed your fish.
This situation in conjunction with warm pond temperatures, large algal blooms and a high pond water pH is a sure fire guarantee that your fish will die. Pond pH has a significant effect on the level of ammonia in your pond. A pond water pH of 8 contains 5% ammonia (toxic) and 95% ammonium (less harmful). As the pH increases the level of ammonia rises drastically. At a pH of 9 there is an equal split between ammonia and ammonium (50% each) ... If you are looking for further information please read avoid fish fatalities in garden ponds control ammonia levels ...
If you want to maintain a healthy garden pond with vibrant healthy fish then you must ensure that water is pumped through your biological pond filter continuously, apart from the odd period when routine maintenance needs to be carried out.
Even then I would advise that you leave routine maintenance to late fall and early winter when the biological activity in your garden pond has practically stopped; that is if you live in the cold Northern states of the USA, Canada and Northern Europe which experiences long cold winter spells … If you are looking for further information regarding how to winterize your pond please read Fall Garden Pond Care - How To Winterize Your Outdoor Pond ...
Under no circumstances must you switch off your pond pump overnight and switch it back on again the next day, as by then it will be too late. Biological pond filters need a constant supply of oxygenated pond water 24/7.