Pond Volume Calculation

Not many of us can afford a gallon flow meter to connect to our water supply when filling our ponds. There is another way to calculate the volume of water in your pond by adding salt. Koi are very tolerant to salt it seems and it has a lot of benefits. The salinity range should be about 0.1% to 0.3% as a long term bath but you can increase it to 0.6% for several days, 0.7% for about 1 day and even carefully up to 0.9% for about 10 minutes to kill parasites, bacteria and protozoa. Don't leave your fish in water over 0.3% for months and months. Parasites will grow resistant to salt and next time you will have to treat with a higher concentration.

Benefits of Salt in the Koi Pond

• Increases protective slime coat - 0.1% - 0.3% concentration
• Aids in absorption of oxygen through the gills - 0.2%
• Will kill many forms of parasites and protozoa - 0.6% or higher up to 0.9% (Carefully)
• Increases Koi's buoyancy making it easier for them to swim
• Decreases osmosis in the fish so their kidneys don't have to work as hard
• Slightly decreases the freezing temperature of the water allowing it to absorb oxygen easier during the winter by reducing ice buildup.

You will need to buy a salt meter that can measure salinity in % or Parts per thousand (PPT) up to 1% and you will need to buy a 40lb bag or two of Solar salt used in water conditioning systems. It's better to completely dissolve some of the salt in a bucket with some pond water. Solid salt can burn gills and fins and if not completely dissolved its easy to overdose your pond possibly killing your fish.

The formula as a starting point is that it takes 1 lb of salt per 100 gallons of water to raise the salinity to .12%. So if you "Think" your pond is about 1000 gallons you will need 10 lbs of salt to bring it up to .12% salinity. Well we don't know the volume exactly but the above will let you know how many bags to buy to get to the desired salinity level.

So to calculate volume you use the following formula:

V=(P/C)x120

V=Volume in gallons
P=Pounds of salt added
C=Change in salinity in PPT (or 10 times the % change)

For example,

I think my pond is about 2000 gallons but I'm not sure. Using the salinity tester measure the salinity of the pond before you start. In my case it was 0.0%. I measured my bags of salt on a bathroom scale and found them to be exactly 40 lbs each.

Slowly dissolve about 1/4 of a bag at a time into a 5 gallon bucket of pond water and using a small aquarium pump, circulate the water until it's all dissolved. Then pour it into the pond around the edges but not directly on your fish. Do this three more times until the entire bag has been dissolved. Let the water circulate through your pond pumps for a while and after a few hours or even the next day, measure the salinity of pond.

In the example I used, I dissolved the entire 40 pound bag. The change in salinity was 0.29%.

So using our formula, V=(40lbs/2.9)x120 = 1655 gallons

Wow, I was off by about 350 gallons!

This is important to know when and if you ever have to dose your pond with medication. An error in the dosing could cause you to overdose and kill all of your fish.

You can salt the pond slowly over time but you have to weigh the salt you put in each time and add it all up when you are done. Don't add water or you will mess up the calculation. Always use pond water to dissolve the salt.

Salt will not evaporate so to reduce the concentration you will need to perform water changes. Concentrations over 0.3% should not be pumped into your lawn. You will have to pump into your toilet and let the sanitation company deal with it. Also remember that two 0.3% water changes are additive to your lawn and could kill your grass. Make sure you water your lawn real good before the second one or wait until after it rains.

Salt is cheap and beneficial to your Koi and at small concentrations of 0.2% or less can be used year round to help your Koi ward of bacterial infections and absorb oxygen easier duirng cold winter months or during the hottest of summer days.