Liming—What’s that about?

By Bob Lusk


With pond management, there are a few constants. One of those is the subject of liming. Should I lime? How much? What kind of lime? While this question seems simple, answers are varied.

The number one reason to lime a mini-pond, or any pond, is to neutralize acidity in the water and bring the alkalinity upward. One of the consequences is a rise in pH.

How to know to lime? Check the water chemistry. If your alkalinity is less than 17 parts per million, add lime. When alkalinity is low, so is pH, typically.

For small ponds, there are a number of reasons to lime. Smaller ponds are often pushed to the limit for fish production. Extra feed with excess fish waste lead to water quality issues. Lime helps buffer the chemistry of water. So, lime is good. Lime is a building block for bones in fish. Lime is needed for natural production of plankton. Without lime, ponds are not nearly as productive, or as safe from chemistry changes.

Beware, though. Lime comes in several forms, and each serves a different purpose. Look for calcium carbonate. That’s the lime most beneficial to your pond. Watch out for hydrated lime…calcium hydroxide. That stuff can cause a fatal spike in pH. That’s not to say drastically low pH ponds couldn’t benefit from hydrated lime. Pay attention to other products and know what you are buying. There’s calcium sulfate…that’s gypsum. Lawn lime products are good. But, dollar for dollar, it’s tough to beat old fashioned aglime, a corn meal textured crush limestone rock straight from the quarry.

If you live in an area of sandy soils and pine trees, you need to study the need for lime. On the other hand, if your pond sits somewhere in mineral rich soils, there may be so much lime that it forms white spots around pond’s edge when it leaches into the soils.

What’s the quantity? How much does it cost? If aglime is available nearby, expect it to cost between $18-30.00 per ton. If you have zero alkalinity, apply at least a ton of lime per surface acre of water.

Do I have to add more, later? Depends. If your pond flushes, the more water that leaves, the more lime you lose. The more you lose, the more you need. The best way to tell is by checking water chemistry from time to time.


Here’s cutlines for the photos.


Lawn lime: For mini-ponds, buying lawn lime by the bag may be a good choice. Apply up to one ton for one acre ponds.


Lime label: Read the label and look for “Effective Calcium Carbonate Equivalent.” That tells you the percentage of usable lime for water.


Liming hatchery pond: There’s a number of ways to apply lime. This pondmeister has a pto powered fertilizer spreader. He just loads the lime, moves around the pond and distributes the product. Effective, and easy. Or, you can do it from a boat, with a feed scoop or a shovel. Be sure you get the most even distribution possible.liming-hatchery-pond