by Joe White, Florida

Courtesy Florida East Coast Koi and Water Garden Society newsletter, February 2003

 

An important bit of data you need to know about your pond is the total gallons. There are several ways to determine this. The most obvious is by using the math formula for calculating volume. However for an irregular shaped pond (which most are) the best way is to meter your water going in to the pond when it is filled. If you don't have a meter, you can time the water going into a bucket and estimate the number of gallons by how long it takes to till the pond. If you did not use either of these methods and the pond is already filled with water what can you do? Well, you can estimate pond gallons by using salt.

 

Just take the pounds of salt added to the pond and multiply by 12. Divide the result by the change in salinity to get the gallons. This means you must test the salt level before and after you add the salt. Here is an example:

 

The salt reading of my pond was .60ppt (parts per thousand) on my Oakton salt meter. I added 40lbs of salt and waited a day before retesting. The reading after adding the salt was 1.10ppt. This is a difference of 0.50ppt or 0.05%.  Note that to convert ppt to percent divide by 1000 and move the decimal two places to the right.

 

Gallons = (Pounds of salt X 12) /change in salinity.

 

40# salt X 12 = 480/.05 = 9600 gallons

 

This is very close to the estimate of 10,000 gallons for my pond based on a combination of using a meter and timing the fill when I first opened my pond