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Pond Volume Calculator: How Much Water Is in My Pond?

    Need to know how much Beneficial Bacteria or salt to use in your pond? Or do you need to know how big of a skimmer or pump to buy? Then you need to know how many gallons of water are in your pond.

    Knowing how much water is in your pond is crucial to pretty much every aspect of pond ownership, from measuring water treatments to buying equipment. That means if you don’t know how many gallons of water are in your pond, you’ll need to break out the tape measure and calculator.

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    How to Calculate Pond Size in Gallons

    Pond Volume Calculator

    For most ponds, for most applications, you can use the following formula to figure out roughly how many gallons of water are in your pond:

    Length (ft.) x Width (ft.) x Average Depth (ft.) x 7.48 = Approximate Gallons of Water in the Pond

    Ponds usually have a kind of funky shape, so just try to get a rough estimate with your measurements.

    This formula is the one we use for pretty much everything at Splash, from figuring out what size pump will work best with a pond to how much Beneficial Bacteria needs to be added. While it won’t give you an exact number (because of factors like shelf depth, rocks and gravel and irregular shapes), it will be close enough for pretty much any maintenance task you need to perform.

    (Note: Some people opt to multiply the final number in this calculation by 0.8 to account for volume taken up by rocks and gravel in the pond.)

    How to Calculate Disappearing Waterfall Size

    Use the same formula as above to calculate the size of a disappearing waterfall. The only difference is you need to take into consideration both the amount of water in the stream (visible part of the waterfall) and the underground basin.

    • Stream Length (ft.) x Stream Width (ft.) x 0.17* x 7.48 = Stream Volume
    • Basin Length (ft.) x Basin Width (ft). x Basin Water Depth (ft). x 7.48 = Basin Volume
    • Stream Volume + Basin Volume = Total Gallons in the Water Feature

    *0.17 ft. is the average depth of most streams. This equates to about 2 inches.

    Disappearing Waterfall Volume Calculator

    How Big Are the Ponds at Splash?

    Not sure what a 1,500-gallon or 800-gallon pond looks like? If you visit Splash, you can get a rough idea of how big your pond is by comparing it to the ones in our display garden.

    The Lily Pad with Two Waterfalls

    Splash Garden Display No. 4

    Approximate Dimensions:

    800 Gallons
    11′ x 8′
    24″ Deep

    The Lotus with Two Waterfalls

    Splash Garden Display No. 5

    Approximate Dimensions:

    1,500 Gallons
    15′ x 10′
    32″ Deep

    The Oasis

    Splash Garden Display No. 3

    Approximate Dimensions:

    4,500+ Gallons
    22′ x 16′
    42″ Deep

    The Turtle Pond with Waterfall

    Splash Indoor Display

    Approximate Dimensions:

    400 Gallons
    40 Sq. Ft.
    18″ Deep

    How Much Bacteria / Salt / Dechlorinator Should I Add to my Pond?

    One of the main reasons pond owners need to know how many gallons of water are in their pond is to help calculate water treatment dosing.

    Below are some of the most common water treatments that customers ask us about at Splash:

    Aquascape Beneficial Bacteria

    8 oz., 16 oz. & 32 oz. Pump Bottles:
    1 pump per 100 gallons at least 1/week

    1 gal. Pump Bottles:
    1 pump per 600 gallons at least 1/week

    Same instructions apply to Pond Starter Bacteria and Cold Water Bacteria.

    Don’t want to worry about remembering your weekly dose? Try an Automatic Dosing System.

    Aquascape Pond Detoxifier

    8 oz., 16 oz. & 32 oz. Pump Bottles:
    2 pumps* per 100 gallons after clean-outs, water changes or any other time a significant amount of water is added to the pond

    1 gal. Pump Bottles:
    2 pumps* per 600 gallons after clean-outs, water changes or any other time a significant amount of water is added to the pond

    *Our recommendation here is double that of the manufacturer to help counteract chlorine spikes that sometimes occur in municipal water sources.

    Pond Salt

    We only recommend adding salt when fish are ill or experiencing issues with parasites. We do NOT recommend low-level salt treatments for maintenance.

    Please click here for more information and specific dosage recommendations.


    We do NOT recommend using liquid algaecide in ponds that contain live animals. Algaecide does not help treat the root of your algae problems -excess nitrites/nitrates in the water – leaving you in a cycle of buying more and more algaecide. Liquid algaecide also poses a risk to pond fish if dosed incorrectly.

    Instead of algaecide, try adding regular doses of Beneficial Bacteria to treat green water, and a variety of plants to combat string algae. Click here to learn more. You can also alternate Maintain and Clear treatment pouches if you have an automatic dosing system.

    If you must use algaecide, add less than the recommended dosage on the container, and keep an aerator running in the pond.

    How Big of a Pump Do I Need for My Pond?

    Pond Pumps York Lancaster Harrisburg PA

    Knowing how many gallons of water are in your pond is the first step to figuring out the best pump for your pond – but it’s not the only step.

    You will also need to know the pond’s head height, plus find a pump that works for your specific application.

    Check out our Pump Selection Guide to learn more.