Biofloc vs. Aquaponics: The Differences Explained

Biofloc and aquaponics are methods of farming fish, focusing on cost and waste management. Biofloc technology is an advanced system where toxic materials, such as nitrates, nitrites, and ammonia, are converted and recycled into food for the fish. In aquaponics, plants use the fish waste as a natural fertilizer, purifying the water for the fish in turn.

The difference in biofloc vs. aquaponics is in the utilization of fish waste. Heterotrophic bacteria in the biofloc system break down fish waste and turn it into protein. In aquaponics, hydroponic plants absorb the waste as nutrients and purify the water, which is then recycled to the fish tank.

Biofloc and aquaponics have more differences, which I will discuss in the rest of this article. Both systems have become quite popular because they are sustainable, eco-friendly, and cost-effective. Besides working as independent systems, some people combine biofloc and aquaponics to maximize production.

The Differences Between Biofloc and Aquaponics

Biofloc and aquaponics are systems in aquaculture that maximize land use and water resources. Biofloc technology is a common way to produce tilapia and shrimp, and fish farms have used this method for years.

Many fish farms have recently supported the integration of Biofloc and aquaponics (FLOCponics) to facilitate better waste management and water purification.

Here are the differences between Biofloc and aquaponics:

The Biofloc technology enhances water quality by balancing nitrogen and carbon in the system. The heterotrophic bacteria break down and convert the fish waste, and any uneaten food in the system is recycled as feed for the fish. In aquaponics, the same bacteria break down the fish excrement and leftover food into nutrients for the hydroponic plants.
Sunlight is critical in the biofloc system. That’s because photosynthesis converts waste, uneaten feed, and excess nutrients into high-protein food for the fish. You can place aquaponics systems indoors or outdoors. However, lighting is essential for the plants, not the fish.
In the biofloc system, heterotrophic bacteria purify the water. However, in aquaponics, plants are critical for water purification.
The fish for Biofloc should be heavy consumers of protein. Examples of filter feeders are shrimp and tilapia. The fish should gobble the food quickly to prevent sludge buildup in the tank. Food excess is not as much of a concern in aquaponics since the plants consume the nutrients.
When deciding what fish to use for aquaponics, the primary considerations are whether they will survive in a warm or cold environment. Biofloc limits the type of fish to keep. You must also consider the size of the fish at maturity and the size of the tank.
You will save on plant food in aquaponics because you will use the fish waste to feed the plants. In Biofloc, the savings will be in fish food because the fish waste will be broken down and converted to protein which the fish will consume.
Fish stocking density in biofloc tends to be higher than in Biofloc systems. In aquaponics systems, the ratio of 1:1 is recommended for the fish tank and grow bed. Sometimes, a balance of 2:1 is okay, as long as you reduce the fish stocking density. Keeping the proper ratio will allow for easy water filtration. However, this is not a concern in biofloc systems.
It is easier to avoid ammonia peaks in aquaponic systems than in biofloc. All you need to do is not overfeed the fish. In biofloc, you need to be more critical of the amount of carbon in the fish feed. You need to get food with a high carbon ratio and additional inputs to raise the levels to 15:1. Most foods have a carbon to nitrogen ratio of 9:1.
Biofloc systems require closer monitoring than aquaponic systems. Since the water in aquaponics gets purified at all times, the risks of toxic buildup are lower than in biofloc. Monitoring bacteria buildup is also critical in biofloc because they help break down the waste into protein and keep ammonia levels low.
Algae growth is discouraged in aquaponics but encouraged in biofloc. That is why you must fish tanks in aquaponics away from sunlight, while those used in biofloc need natural sunlight.
Aeration in aquaponics systems remains the same because there is limited or no algae buildup. You will need to boost aeration in biofloc systems as time goes by because the water becomes murkier over time.
You should harvest fish in biofloc within 4-5 months. Keeping them for longer increases the risk of death. There is no time limit for fish in aquaponics systems since you can use ornamental fish.
pH fluctuations are higher in biofloc systems than in aquaponics. The average pH of fish blood is 7.4, so they can survive in a water pH of 6.5 to 9.0. Lower or higher pH levels will result in the death of the fish. That is why you must test the pH levels several times a day in Biofloc.
Biofloc requires a broader range of monitoring systems. You must monitor total dissolved solids (TDS), electric conductivity (EC), dissolved oxygen, temperature, pH, and oxidation-reduction potential (ORP). Aquaponics is not as demanding since you only need to maintain proper aeration, stable pH levels, and the ideal water temperature.
Anyone can set up and manage an aquaponics system with minimal knowledge. Biofloc is more technical and requires some expertise to operate successfully.
Biofloc systems have variations in color, transitioning from green to brown, depending on feeding rate and sunlight exposure. Algae growth causes the water to become green, but as bacteria levels rise, the water changes to brown. However, the color remains pretty stable in aquaponics tanks since the conditions do not favor algae growth.

Similarities of Biofloc vs. Aquaponics

Biofloc and aquaponics share some similarities despite their many differences. People who have handled aquaponics before have an easier time managing biofloc because they are similar.

Both biofloc and aquaponics use bacteria to break down fish waste.
Aeration is critical for the survival of fish in both systems.
Tilapia is a common fish species used in biofloc and aquaponics.
Both are economical aquaculture systems.
pH levels in both systems need to be balanced to cater to the fish and microorganisms. In aquaponics, you’ll also have to consider the plants. That makes biofloc and aquaponic systems quite delicate to manage.

Advantages of Biofloc

Aquaculturists established the biofloc system to improve environmental control over fish production. The cost of feed, which is estimated to make up 60% of the production cost, and land availability were the primary driving forces behind Biofloc.

Here are the advantages of biofloc aquaculture:

Biofloc technology works as a wastewater treatment that minimizes water loss and waste.
It reduces the cost of food since the waste is converted into protein and consumed by the fish.
The system accommodates high-density fish rearing.
It doesn’t take up much space.
It is highly profitable considering the cost of feeds falls significantly.
Biofloc reduces water pollution.
Limited or no water exchange.
It discourages the use of substandard fish food that affects productivity.

Disadvantages of Bioflocs

Although Bioflocs has several benefits, it is also a complex system with some challenges.

Before setting up a Bioflocs system, you need to consider the challenges to determine whether you can overcome them or not.

Here are the disadvantages of Bioflocs:

Biofloc requires intensive monitoring systems.
Since aeration is critical, the overdependence on electricity increases the costs significantly.
Specialized labor is necessary for the management and monitoring of the Biofloc technology.
The risk of toxicity in the fish tank due to the accumulation of nitrates and phosphate and low water renewal may affect the system’s stability in the long term.
High respiration rates reduce response time should anything go wrong with the system. That is why regular monitoring is critical because a mishap could result in the death of all the fish.
Maintenance of high water quality is sometimes tricky. The water in Biofloc systems serves as a medium to keep fish alive and a place for bacteria and organic production. Finding the right balance for the fish and organic matter to thrive can be an uphill task.
Nitrate accumulation can cause an increase in pollution.

Aquaponics or Biofloc, Which Is Better?

When choosing between biofloc and aquaponics, you need to decide the system that suits you best. Both methods have advantages over the other, as well as shortcomings. There is much to consider before deciding on a better system.

Aquaponics is better if you have a small-scale system, and you would like to combine aquaculture and hydroponics. If you can’t monitor the system regularly, aquaponics is better. However, biofloc is better for high-density fish production, and it’ll save you money on fish food.

When choosing between aquaponics and biofloc, you need to appreciate that one system works for one person, and the other is better for another. Your choice will depend on your goals. Do you want to save on hydroponics food or fish feed? If you don’t have the skill to manage biofloc, you should learn more about it before going ahead with it.

Composition and Nutritional Value of Bioflocs

Biofloc systems comprise:

Aggregates (flocs) of bacteria
Protozoans
Feces
Uneaten fish food
Algae

Each floc is bound together with mucus that the bacteria secrete. Most of the flocs are microscopic, while others are visible to the naked eye. Some bioflocs are large and contain 50 – 200 microns. Low water exchange rates (0.5 – 1% per day) encourage growth and active floc buildup.

Types of Fish Suitable for Biofloc

Not all types of fish are cut out for Biofloc systems. The floc buildup works for fish species that derive nutritional benefits from the consumption of floc.

Some fish species that are good candidates for biofloc systems include:

Shrimp
Tilapia
Carp

These fish species, especially shrimp and tilapia, have biological adaptations that allow them to digest microbial proteins produced in the biofloc system. They also survive in poor-quality water with high solid concentrations.

Some of the unsuitable fish species for biofloc include hybrid bass and catfish. These fish are intolerant of water with high solid concentrations.

What Changes in Water Quality Mean in Biofloc

Transition in water color in biofloc systems, from green to brown, is influenced by feeding rates and sunlight exposure. When the daily feeding rate increases, more waste accumulates, resulting in higher algae growth.

An increase in algae bloom results from ammonia accumulation in the system. The algae help to control ammonia concentrations in the biofloc system. When this happens, the water turns green and becomes thicker. At this point, aeration rates need to be higher to improve oxygen levels in the water.

If feeding rates keep increasing, algae density will keep growing. When this happens, the water becomes dark, preventing sunlight penetration. Algae overgrowth will hinder photosynthesis, and bacteria flocs will start to develop. At this point, solid waste concentrations will become suspended in the fish tank.

More aeration will become necessary to maintain the biofloc system. However, despite all the activities taking place, the water remains green. The water will start changing to green-brown as the feeding rate increases and oxygen levels rise. As the biofloc buildup increases and algae levels fall, the water will become more brown than green.

Sometimes, the changes in the color of the water may not be visible. So, it’s critical to monitor your biofloc system to determine how much buildup is accumulating in the tank.

Ammonia Dynamics in Bioflocs

Ammonia is essential in a biofloc system.

High ammonia levels signify high waste products from the fish. However, in high quantities, ammonia is toxic. You should maintain ammonia in biofloc systems to keep it below toxic levels. However, at the same time, ammonia levels should be within acceptable levels for the bacteria to break the waste down into protein.

In biofloc, the three main components that control ammonia are:

Algae uptake. When the fish waste and uneaten feed in the fish tank get sunlight or UV exposure, algae starts building up in the system. As the algae population increases, bacteria flocs will also grow. As the density increases, it will limit ammonia uptake, causing the system to be more toxic. Having fish that can consume the flocs as fast as they reproduce is critical in keeping this ammonia level at a tolerable limit.

Nitrification. Oxygen levels should increase as ammonia levels rise. Otherwise, ammonia will turn into nitrites, which are toxic to fish. When oxygen levels rise, it will convert ammonia into safe nitrates.

Bacterial assimilation. Heterotrophic bacteria build up in biofloc systems due to high carbohydrate concentration in the water. You can add extra carbohydrates, such as corn starch, molasses, and rice bran, to the system to boost the carbon ratio in biofloc. As the volume of bacteria increases, the demand for nitrogen in ammonia rises.

Solid Management in Biofloc

In biofloc, the solid concentration is from the following:

Fish wastes
Carbohydrate additions
Intense aeration

Solids can be a problem in biofloc systems if the bacteria do not break down the waste quickly. You may also experience some issues if the fish do not consume the recycled feeds rapidly.

To manage solids in biofloc, you should:

Use settling cones to measure solid concentrations per liter of water.

Increase oxygen supply in the biofloc system to make the environment ideal for fish to consume the food.

Use clarifiers sparingly to break down high solid concentrations. Water clarifiers clump small floating particles into large clusters, allowing you to scoop them out of the water.

Controlling the accumulation of solids in biofloc systems is challenging because new growth will constantly pop up. However, having suitable fish species, a high concentration of dissolved oxygen, and ample aeration will help reduce the solid retention time.

Liming To Control Alkalinity in Biofloc Systems

The nitrifying bacteria reduce alkalinity in biofloc systems. These bacteria increase the risk of alkaline depletion, making the water too acidic for fish to survive. Ammonia levels will also rise significantly, affecting your fishes’ health and feeding habits.

Liming agents can help you reduce ammonia levels and increase alkalinity in your system. Substances like sodium bicarbonate are suitable liming agents.

I highly recommend using a pH meter when using biofloc, whether you’re a beginner or a pro. These monitors make keeping your tank healthy so much more straightforward, helping you have the most productive system possible.

How To Prepare Water for Bioflocs

Like aquaponics, you’ll need to pre-treat your water before you get the system running. The water should not only be ready for the fish, but it should be in the right state for bacterial growth.

Here is a guideline to follow when preparing water for biofloc:

Wash the fish tank. Even when working with a new fish tank, you need to eliminate harmful bacteria present in the tank. Wash with fresh water and Potassium Permanganate.
Fill half the tank with water. Bacteria reproduce faster in warm water, so filling 50% of the tank with water makes the environment ideal for bacteria to grow.
Aerate the water. Adding plenty of airstones, pumps, and filtration will increase dissolved oxygen levels in the water.
Add 1kg (2.2 lbs.) of salt per 10,000 liters of water (353.15 cubic feet). The salts help maintain TDS levels in the system. Add Calcium Carbonate (CaCo3) 500mg (0.018 oz) per 10,000 liters (353.15 cubic feet) to help maintain pH. Molasses and probiotics introduce carbohydrates to control ammonia levels and encourage bacteria to accumulate.
Cycle the system. Aerate the tank for 7-9 days before adding the fish.

Do You Need To Change Water in Biofloc?

The essence of biofloc technology is to reuse metabolic waste, save on feeds, and recycle water.

In traditional aquaculture, water change is a requirement because of the accumulation of fish waste and bacteria that cause diseases. However, since biofloc technology involves the breakdown and reuse of fish waste, the risk of harmful conditions is minimal.

You don’t need to change the water in biofloc because the waste in the system is recycled and used as food. The biofloc system will need a zero to 1% water change with the right conditions. However, if the system is not well-maintained, the water will become murky and inhabitable for the fish.

Close monitoring is essential in biofloc systems because there is the risk of the water becoming toxic for the fish.

When the water quality degenerates, you may need to change the water frequently. In the long run, this beats the purpose of biofloc technology because this will raise the cost (and effort) of production.

Why Does Water pH Reduce in Biofloc?

It is easier to maintain pH levels in aquaponics than in biofloc. That’s because there are many activities taking place in the fish tank, and they impact water pH. Often, pH levels fall in biofloc, and this drop occasionally changes the pH to levels below the recommended pH 6.5 – 9.0.

Water pH reduces in biofloc because of nutrient cycling in the system. The microorganisms favor alkalinity consumption, which results in a fall in alkaline levels. If the accumulation of solid material, mainly waste and protein, keeps increasing, alkalinity depletion is likely.

Sodium bicarbonate is vital when operating a biofloc system because it helps maintain its alkalinity. It is rare for pH to rise in biofloc because the conditions only support the loss of alkaline. Measuring pH levels will help ensure the fish tank remains viable for fish sustenance.

Conclusion

Biofloc and aquaponics systems are popular aquaculture systems. Aquaponics is the most popular system in both domestic and commercial settings. However, biofloc technology is mainly used in commercial setups because of the skill and commitment required to maintain the system.