Well, everybody knows that fish live under water and that there needs to be a certain concentration of oxygen in the water for them to survive and thrive. Pond aerator pumps are essential to the health of fish in captivity but they are next to useless if they’re not the right size.

If you’re going to keep fish, and keep them in excellent condition, then you’ll need to invest in the right sized pond aerator pumps for your body of water. Get it right first time and your pump will pay for itself over and over, not just in the turnover of fish but also in maintenance.

**Ensure the Health of your Fish**

For large ponds, you need a high volume air pump in order to ensure a steady air flow. It will keep the dissolved oxygen levels at an appropriate level for the health of your fish, help with adequate filtration and virtually guarantee you an aquatic environment that’s always bubbling at optimal performance.

When sizing pond aerator pumps, you need to know the depth and width of your pond. You should also keep in mind the ambient temperatures surrounding the pond because in summer, water is less efficient at maintaining oxygenation and in severe winters, good gas exchange is vital to avert the icing over of the surface water.

**Calculating the volume of your oblong Pond**

Obviously you need to know how much water you have so you can determine what size pond aerator pump you’ll need to keep it healthy. Use the following calculation:

- Length x Width x Average Depth x 6.23 = Gallons (approximately)

Next, add another 25% capacity to this figure to ensure that the pump you use is able to cope with fluctuations in water levels, and so that it is not an under-performing pump for what you need.

**Calculating the volume of your circular pond**

Measure the diameter of your pond then halve it to achieve the radius. Multiply the radius by itself then multiply by 22. Divide by 7 then multiply by the pond’s average depth. Multiply again by 6.23 then divide by 220. The answer is the volume of your pond – in tons.

- Example: pond diameter of 12ft.

12ft diameter divided by 2 = 6ft radius

6ft radius x 6ft radius = 36

36 x 22 = 792

792 divided by 7 = 113.14

Multiply 113.14 by average depth of pond, e.g. 5ft = 565.7

Multiply 565.7 by 6.23 = 3524.31

Divide 3524.31 by 220 = 16 tons

Calculating the volume or a pond of irregular shape

If you need to size a pond aerator pump for a pond of irregular shape, you simply lay a piece of rope around the perimeter of the pond then measure the length of the rope. Our example is 100ft.

- Divide 100ft by 4 = 25ft

Multiply 25ft by itself to achieve the surface area (25 x 25) = 625ft²

Multiply surface area by depth (e.g. 5ft): 625 x 5 = 3125

Multiply 3125 by 6.23 = 19468 gallons

Divide 19468 gallons by 220 = 88.5 tons

**Choosing a Pump**

You need to choose a pump that will allow circulation of at least 50% of your pond’s capacity in 60 minutes so when sizing pond aerator pumps, you must take with you the relevant calculations (above) for your particular pond.

As a general indication, if your pond holds 1000 gallons, you should buy a pump that discharges at least 500 gallons per hour (GPH) back into it. Always buy pumps that are slightly more efficient than you think necessary unless you’re sure of your calculations.