Ponds and dams can add to the beauty of a property. But if they begin to experience odour issues, the once pleasant water feature won’t have the same effect.
Unpleasant odours in ponds or dams are caused by water quality problems. Gases from these issues bring harmful bacteria that affect aquatic life. Health risks like headaches, nausea, lung damage, and long-term issues can also be caused by the smell.
To remove and prevent the smell, the good news is, there are methods you can use.
Types of Odours that Occur in Ponds and Dams
Here are some odours that might be making your pond or dam smell:
Hydrogen Sulfide (H₂S)
Smells like: Rotten eggs.
Health Risks: Can cause headaches and dizziness. Serious breathing difficulties, unconsciousness, and even death can occur with a high concentration of it.
Cause: Hydrogen Sulfide is produced by anaerobic (oxygen-hating) bacteria that breaks down organic matter in low-oxygen conditions, such as sludge at the bottom of a pond.
Ammonia (NH₃)
Smells like: Urine or household cleaners.
Health Risks: Ammonia exposure can irritate the eyes and skin. It can also interfere with respiratory systems. High concentrations can damage lung tissue and cause long-term health problems.
Cause: Ammonia is released when decaying organic material, such as fish waste and plant debris, builds up in stagnant water.
Mercaptans (also known as Thiols)
Smells like: Rotting cabbage or garlic.
Health Risks: Mercaptans can cause anything from skin and eye irritation to respiratory issues, and death in some severe cases. If the gas accumulates in an enclosed space and you’re exposed to it long-term, it can cause serious health complications.
Cause: Mercaptan compounds are formed through the decomposition of organic materials. If a pond lacks the right levels of oxygen, anaerobic bacteria will thrive and aid in the decay of these materials.
Methane (CH₄)
Smells like: Swamps and rotten eggs if mixed with other compounds.
Health Risks: Methane in small quantities isn’t toxic. However, it’s extremely flammable and can be dangerous in confined spaces as it displaces oxygen, leading to risks of suffocation.
Causes: Methanogenesis is the process that forms methane. Microorganisms in the pond break down organic matter and release methane as a byproduct, especially in oxygen-deprived conditions.
Putrescine and Cadaverine
Smells like: Decomposing meat or “rotting flesh” of animals which is described as a heavy, sickly-sweet stench.
Health Risks: They’re not directly poisonous but these odours can cause nausea and headaches. Their presence is also an indicator of poor water quality and excessive biological waste, and this can harm aquatic life and increase the risk of pathogen growth.
Causes: These compounds are released during the breakdown of proteins usually from dead fish, aquatic plants, or animal remains in the water.
The Reasons Why Your Ponds or Dam Smells
The main reason for foul odours in ponds and dams is the anaerobic (oxygen-hating) bacteria. This bacteria thrives in areas where oxygen is reduced and feeds on organic waste like fish waste, dead plants, uneaten food, and decaying algae. As the bacteria breaks these materials down, they release unpleasant gases.
The gases throw off the balance of the water. And without proper intervention the horrible smell will only get worse.
Here are the main contributors of the bad smells:
Build Up of Organic Waste
Organic wastes like leaves, dead insects, plants, fish waste and uneaten food all serve to add too much organic matter. All of these materials sink to the bottom of the waterbody and begin to rot. In the process, the anaerobic bacteria will begin to take over and produce gases that emit foul odours.
A Build Up of Sludge
Organic waste like leaves, dead insects, plant life, fish waste and residual food all have high organic content. These all sink to the bottom of the water body and begin to decompose. When this happens, anaerobic bacteria will begin to dominate and emit gases that produce foul-smelling odours.
Excessive Algae
Algae blooms start out as only a small inconvenience that quickly becomes a larger problem. As the blooms begin to break up and die in massive quantities, it can result in foul odours. When the algae dies, it sinks and decays, releasing even more organic material for anaerobic bacteria to feed upon. Due to this, the formation of a foul odour is increased.
A Lack of Oxygen and Poor Aeration
Zones with low dissolved oxygen levels are found at the bottom of ponds and dams with poor circulation. Bad smells happen because anaerobic bacteria outcompete the good (aerobic) bacteria in these areas.
How to Treat Odour Issues in Your Pond or Dam
Pond and dam odours can be persistent and unpleasant, but the good news? They’re manageable if you know how to solve the issue. The best way to overcome a foul smelling odour is to treat the root cause.
To do this you need to:
- Improve water quality
- Reduce the organic load in the water
- Restore the balance
Here’s how to do that:
Introduce Beneficial Bacteria (Like Biostim)
Probiotics (good bacteria) keep your pond balanced. This bacteria breaks down sludge and dead plants naturally, preventing anaerobic bacteria from taking over. The answer? Nature assisting nature.
Biostim is an all-natural, 100% line of biological stimulants that incorporate a blend of bacterial cultures to activate and maintain colonies of beneficial bacteria. Enzymes and nutrients are added as well that immediately enhance aerobic (oxygen-favouring) bacteria growth.
These microbes break down organic waste before it becomes a problem. It speeds up the decomposition of sludge and dead vegetation that would otherwise feed “bad” anaerobic bacteria.
You can choose from Biostim pellets, tablets, powder, liquid or the powerful Biostim Accelerator for extra fast recovery after chemical treatments or algae die-offs.
Enhance Oxygen with Aeration
Low oxygen is the perfect environment for bad bacteria to thrive. By increasing aeration in your pond or dam through fountains and water circulation, you’re supporting aerobic bacteria. This is the good kind that keeps your water clean and fresh-smelling.
When there is plenty of oxygen, the odorous bacteria can’t live and the odour will dissipate on its own. Aerobic bacteria flourish in high-oxygen water, decomposing organic matter rapidly and minimising the sludge that anaerobic bacteria feed upon.
Manage Algae Growth Before It Gets Out of Hand
Prevention is everything when it comes to algae. If algae is unchecked it will die off and sink to the bottom, becoming the perfect food source for anaerobic bacteria.
Intervening early is key before the algae spreads and creates even more problems. A lot of pond and dam owners use an algaecide to prevent the growth of algae. If you plan on using this, manually remove as much of the dead algae as possible to avoid fueling sludge build-up and odour.
Pair your algaecide with Biostim Accelerator to make your treatment more effective and gentler on your pond’s ecosystem. If you want to rebuild a healthy population of good bacteria which are often harmed during algae kills, you need this fast-acting formula.
Need a Quick Fix? DAZZeL Eco Plus Has You Covered
If you’re tackling a smelly pond or dam and need a fast, effective solution while longer-term treatments like aeration and probiotics do their thing, DAZZeL Eco Plus is your best bet. This ultra-concentrated, all-natural odour controller is designed to neutralise bad smells at the source as opposed to just cover them up. Made from a blend of plant leaves and herbs, DAZZeL Eco Plus binds to and breaks down the odour-causing molecules responsible for sulphur, ammonia, and mercaptan-based smells.
Originally developed for heavy-duty use in places like wastewater lagoons, meat plants, and oil facilities, it’s safe and effective for ponds, dams, and other water bodies too. It’s particularly handy when you’re still waiting for aeration systems or probiotics like Biostim to balance the ecosystem and starve out the smell-producing anaerobic bacteria.
For best results, dilute before use, as this product is a powerful 20x concentrate.
So if your pond or dam is giving off a bad smell, DAZZeL Eco Plus offers a reliable short-term fix while you work on long-term water health.