Best Beneficial Bacteria for Fish Ponds Guide 2023 (Updated)

Beneficial bacteria supplements are a great way to top up a pond’s natural bacteria levels to further reduce harmful substances and maintain clear pond water. In this article, we’ll explain more about pond bacteria in general, as well as recommend the best pond bacteria products currently on the market!

US Pond Owner? We recommend...

Rescue Water Treatment Beneficial Bacteria	Atlantic Water Gardens Beneficial Bacteria	Eco Labs Beneficial Bacteria

UK Pond Owner? We recommend...

Evolution Aqua Beneficial Bacteria	Blagdon Beneficial Bacteria	NT Labs Beneficial Bacteria

What is Beneficial Pond Bacteria?

Our ponds are filled with billions of hard working microorganisms, called aerobic bacteria, which provide the essential duty of year-round pond clean up and maintenance. The reason why they’re “aerobic” in nature is because they thrive in oxygenated conditions, whereas anaerobic bacteria (the bad kind) thrive in low-oxygen conditions; such as an unclean filter box. Aerobic beneficial bacteria work to convert harmful substances, such as ammonia from organic waste, into less harmful nitrites, and then nitrates – a process called the nitrogen cycle.

This process occurs naturally in all garden ponds, and does not require the addition of commercial bacteria supplements for the process to work. Beneficial bacteria will begin to grow in your pond the moment water touches the pond lining, and will slowly multiply and establish as your pond continues to mature.

One place in particular that bacteria love to live is within your pond’s biological filter media. Inside your filter, mechanical media will physically remove larger debris, and biologically optimized media will create housing for bacteria to colonize so they can break down harmful substances that stick to their surface. Even though there is beneficial bacteria living throughout the entire pond, the greatest concentration of substance breakdown occurs within your highly concentrated filter media.

Do I need to use beneficial bacteria products? Are they safe?

Beneficial bacteria will naturally colonize most ponds over time, but sometimes bacteria levels can be depleted, or the pond environment may not be suitable for maximum bacteria growth. In these cases, especially if you have koi or goldfish, supplementing with a natural beneficial bacteria product can be extremely helpful to maintain clean water and reduce harmful substance build-up. Since it’s impossible to “overdose” on beneficial bacteria, your pond will only gain benefits from having more present. In most cases, more beneficial bacteria = cleaner, clearer, healthier pond water.

Beneficial bacteria supplements contain the same bacteria strains as those found naturally in ponds, so all a supplement product will do is greatly enhance the levels already present. Although we cannot identify every single bacterial strain, the type of beneficial bacteria in your pond and within bacteria supplements are known as heterotrophic organisms.

One of the primary metabolic processes of these kind of organisms is called heterotrophy (hence the name), which is the breakdown of organic matter into its constituent inorganic compounds, like nitrates and phosphates. These inorganic compounds are readily used by pond plants, which will, in turn, produce more organic substances for bacteria as they make use of minerals and sunlight to grow. This creates a natural cycle that is at the heart of a healthy ponds eco-system.

Will adding beneficial bacteria help prevent algae growth?

Since most algae types have the same nutritional requirements as pond plants, it should be noted that most beneficial bacteria will not actually help reduce algae in your pond. Pond plants will directly compete with algae for nutrients, but if you do not have a planted pond, beneficial bacteria can actually promote algae growth. This is because they benefit from the inorganic compounds that are produced after bacteria break down organic substances; similar to how garden plants benefit from natural compost.

If you suffer with pond algae, we recommend removing as much algae as possible before adding beneficial bacteria for the best results. This can easily be achieved by running a UV clarifier for a few weeks to clear the green water and kill the algae. And if you’d rather not buy a beneficial bacteria product, we do have some DIY methods to grow your own beneficial bacteria. 

Main Benefits of Beneficial Bacteria Products (Why It’s Good)

Bacteria has an incredibly important job in garden ponds, but what are good reasons to supplement with extra beneficial bacteria on top of the natural levels? Some of the main reasons why pond owners choose to add beneficial bacteria products are below:

1) Improves Water Quality

If you have a pond with fish, especially a heavy stocked or small pond, supplementing with beneficial bacteria can help improve fish health and overall water quality. Fish produce waste, which increases harmful substances in the water, such as ammonia. Beneficial bacteria in your pond and filter media will break this down into harmless substances, but in some cases, there just isn’t enough bacteria present to reduce levels sufficiently.

If you have a lot of fish, or fish in a small volume of water, the amount of ammonia can quickly rise to dangerous levels. The best way to combat this to increase the size of your biological filtration system – the beneficial bacteria! Most bacteria supplements have been designed with fish keeping in mind, and the bacteria is optimized to quickly grow and reduce organic waste which causes ammonia problems. If you have fish in your pond with plenty of aeration, there are really no drawbacks in adding more beneficial bacteria to your waters, and it is something we recommend to most fish keepers.

2) Reduces Filter Maintenance (Better Efficiency)

The bulk of your beneficial bacteria will be in your pond’s main filtration system. Biological filter media is usually optimized for maximum surface area so the highest number of bacteria are able to grow. With that said, if you’ve recently added new biological media or just cleaned your current ones, adding new beneficial bacteria to the filter box can help boost the numbers before they can take a dip. Adding more bacteria to your filter will also reduce overall cleaning and maintenance, as the new bacteria will be more efficient at breaking down organic debris and substances. Filters with healthy bacteria populations rarely require cleaning, and the biological media can usually be left almost indefinitely so long as bacteria populations remain healthy and stable.

3) Helps Establish to New Ponds

Beneficial bacteria supplements are especially helpful for new pond builds or new filter systems as natural bacteria levels have not yet had time to become established. This is especially important if you have fish in your new pond, as bacteria will need to be present to begin breaking down organic waste. For a new pond it could take months for natural bacteria levels to increase to a sufficient level, and a new filter on an established pond could also take weeks. Adding concentrated bacteria directly to your new filter box, or directly across your pond water, will provide a massive boost in levels and begin bacteria colonization at a much faster rate.

4) Improves Water Clarity & Polish

Although beneficial bacteria cannot magically make pond water crystal clear, they can certainly be a major contributing factor towards overall water clarity. Excess organic substances are a primary cause of cloudy water, mostly due to excess proteins from fish and feed, and beneficial bacteria are able to help break this down. In fact, a slow decrease in water clarity over time is almost always due to some kind of organic substance imbalance. Beneficial bacteria, in most cases, will be able to help combat this imbalance and bring the pond back into shape.

Maximizing the Benefits from Beneficial Bacteria

Beneficial bacteria will help control natural organic substances produced by fish, but cannot remove color pollutants or heavier organic compounds.  Beneficial bacteria will not help with dirty water from sediment, or green water caused by algae, and also cannot remove some organic pollutants. To get the best results from beneficial bacteria you can combine it with a range of products to maximize its efficiency and drastically improve pond health and water clarity.

1. Beneficial bacteria products should NOT be added to a pond with low aeration (oxygen) and high waste, as the bacteria will likely just die off in these conditions and contribute to sludge. Beneficial bacteria work best in highly oxygenated waters with a controlled bio-load, so you may need to perform a clean up and add extra aeration to ensure bacteria can perform optimally.
2. Since beneficial bacteria cannot remove algae, you should eliminate all green water before supplementing so algae numbers do not increase. A UV pond Clarifier would be perfect for this.
3. Heavier organic pollutants, such as chlorine and pesticides, cannot be removed by biological media or bacteria. Activated carbon can be supplemented alongside beneficial bacteria for great results.
4. Some pond bacteria supplements are better suited for different jobs, with the ones here being great boosts to biological filtration. To combat things like bottom muck, or sludge, consider bacteria based tablets which are heavier and designed to sink. These are natural and can be used alongside other bacteria based products.

Tips for buying the best beneficial bacteria product

As well as maximizing benefits by supplementing with other products, you can also ensure you pick the best beneficial bacteria for ponds. Not all bacteria products are made equal, and although most contain the same natural heterotrophic bacteria strains, the concentrations can vary, as well as additional ingredients. Some bacteria are also more optimized to work under certain temperatures, so this also needs to be taken into account. Some of the things to consider are:

1. CFU, or colony-forming units, is the amount that bacteria can divide (multiply) under controlled conditions. Basically, the higher the CFU contained within your bacteria product, the faster your beneficial bacteria will grow, divide, and establish themselves.
2. The temperature range bacteria work most effectively is another point to consider. Most beneficial bacteria are optimized for warmer temperatures, so would be best to dose in the spring and summer. Other bacteria are designed for colder temperatures, and would be ideal for autumn. Some bacteria will also work fine in all conditions.
3. Another consideration is how the beneficial bacteria is added to your pond, which may be important depending on the reason you need the bacteria. For example, bacteria balls which sit inside a mesh bag within your filter would be ideal for improving filtration. For water clarity, a bacteria which is spread across your pond as a liquid may be better suited. Most choices are fine, as bacteria will eventually begin to colonize all areas of the pond, but, the quicker the better!
4. Although not as important as the other points, some beneficial bacteria will also contain additional beneficial ingredients to supplement water quality and fish health. You can commonly find vitamins, enzymes, and other natural ingredients included in some products which may help with plant and fish growth.

Best Beneficial Pond Bacteria Reviews 2023 (Updated List)

Due to the different brands available between the US and UK markets, we’ve researched and divided our categories to provide both American and UK pond owners a review on the best beneficial pond bacteria supplements currently available. We have listed below our best pond bacteria picks available to both the US and UK market.

Before Adding Bacteria

US - Best Pond Bacteria

1) Rescue Water Treatment Beneficial Bacteria Review

One of our favorite beneficial bacteria treatments is Rescue Water Treatment’s highly concentrated bacteria and enzyme solution for garden ponds and lakes. This bacteria formula contains an optimized formula designed for maximum performance in warmer temperatures. The product works great in both ponds and lake, and is optimally designed for the removal of ammonia and substance (muck) reduction at the pond floor. 

On top of natural bacteria which will break down harmful substances, it also contains a blend of electrolytes, enzymes, and other probiotic microbes to help improve water clarity and reduce bottom sludge. The bacteria does not require a mesh bag as it’s alreadty liquid and dissolves immediately in water, so you can spread it evenly across your pond surface. A very good product for heavy fish stocked ponds or large ponds heavy in debris as you get a lot for your money here!

How to use: Intended for water temperatures ideally above 55 °F (13 °C). Half a cup per 1000 gallons weekly.

2) Atlantic Water Gardens Beneficial Bacteria Review

A highly concentrated beneficial bacteria treatment designed to work all year round, in both warm and cold conditions. Atlantic Water Gardens Bio-Max bacteria contains a combination of natural denitrifying bacteria and powerful enzymes that work to break down fish waste, debris, and sludge. The product comes in the form of a liquid, rather than a powder, with every ounce of bacteria treating up to 3,000 gallons of pond water. This bacteria is great for biological filters or waterfalls, and works efficiently during all seasons.

The best time to add the bacteria would be at the start of spring, or end of fall, or during a heavy water change to increase bacteria levels. It does not require a mesh bag, and is installed using the measured cap included with the bottle. Would be a good choice for filter systems or to boost overall pond health!

How to use: 1 ounce of bacteria treats up to 3,00 gallons of pond water. Apply weekly until desired clarity is achieved.

3) Eco Labs Beneficial Bacteria Review

A beneficial bacteria product with koi and goldfish keeping in mind! Eco Labs Microbe Lift is a 100% natural bacteria and enzyme supplement designed to create a cleaner and healthier environment for fish to grow. Its highly concentrated bacteria strains break down harmful substances, such as ammonia, which can effect fish growth and health.

The product is optimized for warmer conditions, so would be ideal for fish ponds during spring as a kick-start to summer. The reduction in ammonia, nitrites, and sludge, also helps deter flying pests from laying eggs in the water, such as mosquitoes.

The bacteria is best added with a larger initial dose, and then slowly reduced to a maintenance dose after a few weeks. This maintenance dose can be kept up so fish retain a cleaner and healthier environment. The bacteria comes in liquid form, and includes a detailed dosing chart for easy application. The formula is 100% natural and safe for both fish and pond plants. A great beneficial bacteria for koi or goldfish!

How to use: 1 quart treats approx 5,000 gallons for the initial application. For the next 4 weeks add 12 oz per week, and then a monthly maintenance of 12 oz per month.

UK - Best Pond Bacteria

1) Evolution Aqua Beneficial Bacteria Review

A great choice for improving pond filter efficiency, or for new filter systems! Evolution Aqua’s PurePond bacteria comes in the form of small balls containing millions of natural beneficial bacteria strains. These bacteria are added to a mesh filter bag and then added directly to your filter box, where they slowly colonize your biological media and pond water. Due to their application and close proximity to the filter, this treatment is perfect to boost under-performing biological media or for a new filter which requires fast bacteria establishment.

The bacteria work the same as naturally occurring pond bacteria, breaking down ammonia and nitrogen from decomposing debris and fish waste, and have been optimized for improving water clarity.  The best time to add this bacteria is at the start of spring to kick-start a filters biological filtration system ready for the rest of the year. A filter bag is highly recommended for best results, but not included, so you would need to purchase one separately. We recommend Fluval filter media bags, as the size is ideal for the bacteria balls.

How to use: For best results, add bacteria balls to a filter media bag and place in biological section of filter. Use 250 ml of bacteria balls per 5,000 litres of pond water, and replace monthly.

2) Blagdon’s Bio-activator Beneficial Bacteria Review

A concentrated beneficial bacteria treatment designed as a pond kick-start in early spring, or for new pond builds. Blagdon’s Bio-activator bacteria supplement contains billions of denitrifying bacteria to help reduce fish waste and harmful substance buildup. The product works best in early spring and is dosed monthly all the way through to October. This provides fish the best environment for hibernation/torpor during colder winter months.

The bacteria is optimized for free-swimming substance breakdown and works well to neutralize ammonia and nitrogen from pond fish. It doesn’t work well to reduce sludge, however, so this needs to be taken into account.

The bacteria comes in the form of a liquid, so needs to be spread evenly across your pond surface in areas of good water flow. The bottles comes with a convenient measuring cap, and 25ml of bacteria can effectively treat around 900 litres (250 gallons) of pond water.

How to use: Shake well and apply evenly across your pond water during Spring. 25ml will treat up to 900 litres of pond water. Repeat dosage every 5 days for 4 doses total, then once a month until October.

3) NT Labs Beneficial Bacteria Review

A beneficial pond bacteria product designed to provide biological filtration for filter-less ponds, but also an ideal solution for regular ponds as a top-up or to improve health. NT Labs Live Filter bacteria contains naturally occurring beneficial pond bacteria optimized for fast colonization and waste breakdown.

If used in a natural, fish-less pond, the bacteria can provide enough biological filtration for the pond to flourish, without the need of a dedicated filter box. In a pond containing fish and a filter system, the bacteria are great for improving the efficiency of filter media and reducing harmful substance buildup overall.

This product is optimized for warmer temperatures, and is best used in early spring ready for summer. It is 100% natural and harmless to both fish and plants. It comes with a built-in measuring chamber and every 10 ml of bacteria can effectively treat around 200 litres of pond water. This bacteria would be ideal for smaller ponds, even container ponds, or as a top up to a filter system in a larger pond.

 How to use: Shake well and apply evenly to pond water or directly to filter box. Approx 10 ml treats 200 litres of pond water per week. Apply double dose for 1 week and then a single dose once a week following.