Pond Management Blog

Why Does my Pond Smell?

Do you dread changes in the wind because the smell of your pond or lake wafts into your home? Do you avoid gatherings or cookouts down by the water because of its unappealing odor? You’re not alone. But you can fix it.

Let’s first look at the causes of pond or lake odor. This unpleasant smell primarily comes from at least one of these three sources:

1. Rotting Plants, Fish, and other Organic Matter:

When something rots, it smells—this is a simple fact of life that has us routinely taking out the trash and hunting through the refrigerator for foreign smells.

But, what occurs in lakes and ponds that make the odor so pervasive?

It’s the lack of oxygen. Many rotting things in your pond are digested by aerobic (oxygen breathing) bacteria, and this occurs both quickly and largely without odor.

If given enough oxygen, these hungry little bacteria will clean all the odors and decaying matter out of your pond. Unfortunately, this is not what happens in most ponds—instead, stagnant water that is found in so many ponds has the tendency to develop into distinct temperature layers.

Water warmed by the sun remains toward the surface, and cooler, denser water stays on the bottom. Being sealed in by the upper, warmer layer, the bottom layer receives no oxygen. Eventually fish and bacteria use up all the available oxygen in this area, and this is when things get bad.

What happens is that all inanimate organic matter (dead fish, leaves, grass clippings, sticks, fish waste, dead plants) sink to the oxygen-less, or anoxic, area at the bottom of the pond. Here, the only breakdown and digestion that occurs is done by anaerobic (non-oxygen breathing) bacteria.

Not only are these bacteria seventeen times slower at breaking down organic matter than aerobic bacteria, but they also produce nasty smelling pond odors as a byproduct. These odors include the rotten egg-like hydrogen sulfide, methane, and ammonia.

Ever see bubbles rise to and burst on the surface of your pond? That’s likely anaerobic bacteria, releasing their pungent pond odor byproducts.

Learn how to stop this from happening to your pond.

2. Turnover:

Pond or lake turnover is often a reason why your water occasionally smells really bad. It occurs at least twice a year - once in the spring and once in the fall (sometimes more if there are heavy rainstorms). In these instances, the upper and lower levels of your water body mix together.

The result is a body of water that is low in oxygen and high in noxious gasses (this is very dangerous for fish and can result in a massive fish kill). Now, all of the bad odors and decaying material that were trapped at the bottom are mixed into the water column all at once, making your water smell awful.

3. Odor Producing Algae:

Certain kinds of algae simply smell bad. Ponds with heavy concentrations of cyanobacteria or chara algae, for example, will emit a musty, earthy odor.

So, not only will your pond look bad because of the large algal blooms, but it also smells bad because of the algae!

The Solution to Lake and Pond Odors:

It should be clear at this point that you can't simply sit by and hope the pond smell goes away. You can keep dreaming, but it just won't happen. So, what should you do? (Please, for your own sake, don't look to pond fountains as a solution. Will it look nice? Possibly. Will it stop the problem? No. And neither will pond chemicals so step away from those as well.)

Diffused pond aeration is your best bet. There's no way around it. Adding oxygen from the bottom, up, this type of pond management has proven to solve pond problems more effectively and efficiently than its alternatives. Adding ample oxygen in this way will allow for aerobic digestion to occur again in your pond, creating a quicker and much less odorous break down of excess pond nutrients.

Find out exactly what you need from a Pond Expert.

Some diffused pond aerators are better than others, but anything is better than doing nothing and being forced to endure another summer in the company of a rank pit of a pond.

The best solution to your pond or lake odors is in Eco-Friendly Pond Aeration with the MARS Aeration System, which targets the causes of odors by doing the following things:

• Oxygenating ALL areas of the water column so aerobic bacteria can get to the organic matter and break it down in an entirely odor-free manner

• Mixing the entire pond from top to bottom, preventing layering and the harmful, odor-producing effects of pond turnover

• Preventing algae growth by promoting breakdown of the organic matter before algae has the chance to use it as a source for growth

The MARS Aerator’s patented Double Bubble™ Technology both mixes & aerates your pond—keeping it healthy, clear, and most importantly, odor free!