Bradshaws Banner

Order Bradshaws Catalog button


Algae & ponds

Ponds & filters

Pond plants

Ponds & water gardens

Pond & fountain pumps

Top ponding tips


Pond liner sizes

Tensor pondvac

Oase Pondovac 3

Hozelock Cascade pumps

Oase pressurised filters

Maximus fountain pumps

Olympus Filter Pumps


Never Stop Your Fish Pond Pump Unless For A Couple Of Minutes

Never switch off your pond pump for more than a few minutes if you keep fish in a garden pond. A circulating water pump drives a fountain or a waterfall and it adds character and movement to your system. However ...... Its most important job is to provide life-giving oxygen to bacteria in the fish pond bio filter.

A water pump works just like your heart does. The heart's job is to continuously replenishes your vital organs with freshly oxygenated blood. The source of the pond oxygen is not air directly rather it is oxygen transferred from the air and then dissolved in water (air contains about 20% oxygen at sea level).

Not only fish in a pond need oxygen ... the nitrosomonas and nitrobacter bacteria in pond filters also need oxygen to be able to survive and purify the garden pond water. These nitrosomonas and nitrobacter bacteria use up large amounts of dissolved oxygen and this oxygen needs to then be replaced.

Think of running 2 pumps in a fish pond to make sure you always have a back up and in any case this arrangement allows you to save quite a bit of money if you choose the system properly.

How oxygen is made available to your koi or goldfish as well as nitrosomonas and nitrobacter bacteria ....

  • Water absorbs oxygen at any interface between water and air. Droplets absorb oxygen from air more efficiently than large surface areas like the actual pond surface. Fountains work on this principle.

  • Colder water holds more oxygen than warm water and windy days are better than still days for absorbing oxygen because they effectively increase the surface area of the pond in contact with the air through the action of making waves. The waves also serve the purpose of mixing the oxygen rich surface layers with water deeper down ... this happens as you'll often notice when waves crash against a lake's bank ... here you'll see foam collecting. Water returning from this bank side tends to sink to the bottom layers of the lake on its return journey up-wind (there is a constant recirculation of water caused by wind action).

  • Water has more oxygen in it during the day than it does at night especially if there are pond plants growing in the pond because the pond plants absorb oxygen during the night and release it during the daylight while the photosynthesis process is taking place.

  • A waterfall and a fountain are extremely useful in a pond because they increase that interface between water and air.

Dissolved oxygen is used by your fish to breathe and most people do realise this. What people don't often realise is that water as it passes through the garden fish pond filter has oxygen removed from it. The bacteria in your biofilter use this oxygen to help them "digest" ammonia "food" from fish waste which is also dissolved in the pond water. Let me explain the process in a simplified but essentially accurate way ...

  • In order to digest ammonia from fish metabolic processes each bacteria needs a small amount of oxygen. This oxygen chemically combines (in fact oxidises) with the nitrogen containing ammonia molecules to become nitrates. Ammonia and its chemical formula is NH3. Notice that the ammonia formula contains no O ... for oxygen .... only N for nitrogen and H for hydrogen.

  • The nitrosomonas and nitrobacter bacteria, convert the waste ammonia to nitrates by removing oxygen from water and chemically swapping the "H" for "O" . What was initially NH3 now becomes NO3 (chemical formula for nitrate). This is what's happened ...

  • The nitrosomonas and nitrobacter bacteria have removed the H from ammonia and exchanged it for 3 oxygen atoms. The H dropped from the ammonia molecule also combines with more O to form H2O ... water. This process helps to explain why a considerable amount of oxygen is needed to allow the bacteria to do their work. The only place the oxygen can come from is that dissolved in the water.

So now you know .... never switch off your pond pump for any length of time if you keep fish and certainly never during feeding.

Different types of pumps ...


Best in Class

Pond additives

Pond vacuums

Water features & ornaments

Pond Filters

Fish food

Pond lighting

Pond plants

Garden ponds

Pond pumps

Pond Tools


Polyex liner exclusive to Bradshaws

Complete Pond Kits

Pond Treatments

Oase Pondovac 3


Site Map | Bradshaws store items