RoadtoBiofloc

Water Preparation for BIOFloc Fish Farming

Let’s discuss Water Preparation For BIOFloc Fish Farming process in a scientific way. The details of the how-to prepare Water for BIOFloc Fish Farming is mention in a step-by-step manner to make you understand better. And you can follow this guideline while preparing your own Water Preparation For BIOFloc.

Step1 (Tank Hygiene): Prior to adding water into the tank, it should be properly sanitized. Use Potassium Permanganate i.e KMNO4 (Antifungal Agent) solution to wash the tank and leave it for 24 hours and clean it. This solution helps to kill all the unwanted bacterias in the tank.

Step2 (Water Quality Analysis): Check the water parameter to ensure it suits the BIOFloc environment. If you are planning for a commercial scale, then water must be checked in laboratories. It will be good if the water has negligible or zero Pathogens (which may destroy BIOFlocs). It’s better to get your water checked for IRON, Chlorine, Hardness, etc. These are very basic tests even you can do it and all the test kits are available online. 

• IRON Test Kit –> click here
• Chlorine Test Kit –> click here
• Hardness Test Kit –> click here

The salinity of Water: It’s a crucial component of the BIOFloc system. The salinity of water depends upon the type of fish you want to cultivate. Every aquatic animal has a different salinity level, so you need to check which type of fish/shrimp you want to grow accordingly maintain the salinity level of the water. Salinity Meter (Refractometer) helps to measure the salinity of the water i.e. salt content in the water.

The study suggests that rohu fingerlings can be reared in coastal water with a salinity of up to 6% with 100% survival rate.

Total Dissolved Solids (TDS) in Water: According to World Health Organization, TDS level less than 300 mg/liter is considered as excellent, between 300 and 600 mg/liter is good, 600-900 is fair, 900 – 1200 is poor and TDS level more than 1200 mg/liter is unacceptable. TDS Meter helps to measure the TDS Levels of the water, it not only measures the salt but also measures other dissolved solids. But in BIOFloc usually, the role of TDS is ignored.

PH Monitoring: It helps to understand the acidic or alkalinity of the water. Leave the water tank in aeration for 24 hours and measure the PH. If the PH value differs or it’s below the required PH level, then you must add Calcium Carbonate (CaCO3) to maintain the required pH level of water. Basically CaCO3 never dissolves in clean water, it only dissolves where it finds the acidic nature of the water. The CaCO3 doses will be 0.05 gram per liter. Basically it helps to stabilize the PH Level in Water.

Optimum Aeration: The tank water must be aerated for 48 hours, it helps to oxidise the water and evaporates unnecessary chemicals from the water. The Dissolved Oxygen (DO) level should be within the range of 5-6. DO level below 4 or above 7 can create stress level for the fishes. Dissolved Oxygen (DO) can be monitored using DO Meter or DO Test Kit. DO Meter is bit costly compared to DO Test Kit.

Role of CaCO3: Calcium Carbonate basically helps to maintain the PH Level. You need to add CaCO3 if the PH value is fluctuating or below 5. Basically we add CaCO3 before adding Probiotics. Calcium Carbonate (CaCO3) doesn’t react with pure water but, it does react with carbonic acid that is water with dissolved carbon dioxide, to produce soluble calcium bicarbonate. Add CaCO3 in the night for better results.

Required Quantity → 0.05gm/L

1000L →  50gm | 5000L → 250gm | 10000L → 500gm

Molasses and Probiotics: When all the above condition satisfies, you need to add Molasses and Probiotics in the water. This is standard equation you need to follow;

Molasses / Jaggery (0.1 gm/L) + Probiotics ( 100b cfu = 0.04 gm/L)

For Optimum Results (Jaggery) – 0.1 gm/L

• 1000 L 100 gm
• 5000 L 500 gm
• 10000 L 1000 gm (1 Kg)

 

For Optimum Results (Probiotics) – 0.04 gm/L

• 1000 L 40 gm
• 5000 L 200 gm
• 10000 L 400 gm

Ensure the Probiotics that you use, should be 100 billion CFU. The temperature of the water should be maintained at 26-30 degree for better growth of the bacteria. You need to maintain the required PH and temperature. And the water must be in good aeration for optimum growth.

Take a bucket of water from the BioFloc Tank, mix Jaggery and Probiotics. Uniformly put this mix in the BioFloc Tank.

Ensure the BIOFloc Tank is well aerated and it will take up to 7 days to develop the floc in the tank.

Role of Sea Salt: At the initial stage no need to add Sea Salts, it might hamper the initial bacterial growth.

When you add salt at the initial stage, it slows down the floc development process and sometimes floc don’t grow. Salt doesn’t kill the bacteria but it slows down the process. Salt will be added into the system when the floc is fully developed and depending upon the fish you want to cultivate. Because salinity differs fish to fish. Check the optimum required salinity of the fish that you want to cultivate.

Optimum Quantity of Sea Salt 1 gm/L

• 1000 L 1000 gm (1 Kg)
• 5000 L 5000 gm (5 Kg)
• 10000 L 10000 gm (10 Kg)

Step3 (Fish Introduction): Now the BIOFloc Tank Water is ready to use. Before you introduce nursery fishes into the tank, it’s recommended to sanitize the fishes, so that harmful bacteria will not get introduced to the BIOFloc tank.

What is Nitrification Process in BIOFloc?

It is the biological nitrification process of breaking down Ammonia into Nitrate. When we give Nitrogenous sources in the form of Fish Feed or Fish Excretas into the pond, it decomposes and produces organic sludges in the bottom of the pond. Ammonia and Ammonia Ions are produced from sludges. Excess ammonia creation inside the pond may kill the fish if it is not controlled. Controlling the Ammonia in aquaculture is called Nitrification Process. Let’s discuss how the nitrification process works.

In the Nitrification Process, the Total Ammonia Nitrogen (NH3 + NH4+) gets Oxidized and form Nitrite (NO2–) then again Oxidized and converted into Nitrate (NO3).

The bacteria which converts Total Ammonia Nitrogen into Nitrite (NO2–) is called Ammonia Oxidizing Bacteria (AOB). These AOB are also known as Nitrosomonas Bacterias.

The bacteria which converts Total Nitrite (NO2–) into Nitrate (NO3) is called Nitrite Oxidizing Bacteria (NOB). These NOB are also known as Nitrobacter Bacterias.

Between Nitrite and Nitrate, Nitrite is more harmful to the fish as it enters into the body and affects the immune and blood circulatory system and fish get killed.

So these Nitrosomonas and Nitrobacter Bacterias are used to remove harmful ammonia from the system.

But mostly in Biofloc System, Heterotrophic Bacteria are used to remove ammonia and convert undigested feed into micro-bacteria protein, which is known as FLOCS. These flocs again are eaten by fishes, which helps to lower down the FCR.

What is Carbon to Nitrogen Ratio i.e. CN Ratio in BIOFloc

Carbon to Nitrogen Ratio (CN Ratio) is a process of controlling the amount of Nitrogen in water. Most popular CN ratios are 10:1 and 15:1, which means in CN Ratio 10:1, you need 10 Carbon Sources to kill 1 Nitrogen. In aquaculture, CN Ratio is calculated based on Protein Percentage of Feed and Total Ammonia Nitrogen (TAN)

CN Ratio with Zero Water Exchange

The CN Ratio Calculation is based on Fish Feed Protein Percentage and the below chart shows the CN Ratio of the feed materials.

Protein Percentage (%)       CN Ratio

• 15                                             21.5
• 20                                            16.1
• 25                                            12.9
• 30                                           10.8
• 35                                            9.2
• 40                                            8.1

If you are using 30% protein feed then according to the above chart the CN Ratio of 10:1 is fulfilling. As per the studies, the CN Ratio of 10:1 and 15:1 are more successful. It has been proved the CN Ratio of 10:1 does not require even water exchange.

In a BIOFloc system, it’s recommended to feed low protein feeds. You will have better control over Ammonia and the mortality rate will be less.

Here is an example;

Let’s say the tank contents 100kg of fish biomass and you are feeding 4% of the bodyweight which equals to 4kg feed (4000 grams of feed)

The feed is made up of with Carbohydrates Proteins

Let’s calculate Carbohydrates in feed;

4000 grams of feed contents 90% of dry matter i.e. 3600 gram and 10% moisture i.e. 400 grams on it

Out of 90% of dry matter i.e. 3600 grams, 70% get wasted i.e. 2520 gram and only 30% get digested by fish

For C:N Ratio calculation, you need to consider 70% waste i.e. 2520 gram, because this 70 % of waste is responsible for creating ammonia inside the tank. Don’t calculate CN ratio on the basis of total feed given to fish i.e. 4000 grams.

It’s known that feed contents 50% of carbon in it. So, 1260 grams of Carbon can be found on 70% of waste feed i.e. 2520 grams.

So every day you are adding 1260 grams of Carbon into the water.

The feed that we are using here contents 30% of protein i.e. 30% of 2520 = 756 gram

In 756 gram of protein, Nitrogen contents 16% = 120.96 gram (N)

If you are using BIOFloc in a proper and scientific way then you no need to add Carbon into the tank. 

If you look at the C:N Ratio value its 1260:120.96 which is 10:1 ratio.

C:N Ratio 10:1 = 120.96 x 10 = 1209.6 gram

We already have Carbon of 1260 gram = 1209.6 – 1260= (-50.4) gram – Zero Carbon needed

C:N Ratio 12:1 = 120.96 x 12 = 1451.52 gram

We already have Carbon of 1260 gram = 1451.52 – 1260=191.52 gram Carbon needed

C:N Ratio 15:1 = 120.96 x 15 = 1814.4 gram

We already have Carbon of 1260 gram = 1814.4 – 1260=554.4 gram Carbon needed

Now let’s calculate how much carbohydrate is required to neutralize the Nitrogen.

• Sugar Contents = 42% Carbon 
• Molasses Contents = 22% Carbon

In 1kg Sugar, you will get 420 gram of Carbon & in 1kg of Molasses it will be 220 gram of Carbon

For maintaining C:N Ratio of 12:1, you need 191.52 gram of Carbon

• You need Carbohydrate (Sugar) = approximately 460 grams
• You need Carbohydrate (Molasses) = approximately 870 grams

 

C N Ratio Based on Total Ammonia Nitrogen (TAN)

Let’s consider the Total Ammonia Nitrogen (TAN) in the BIOFloc Tank is 2 PPM (Parts Per Million or Milligram Per Liter)

For a 10,000 Liter Tank it will be 10,000 x 2 = 20,000 mg TAN

Lets convert mg to gram = 20000 mg / 1000 = 20 g TAN

• For C:N Ratio 10:1 = 10 x 20 = 200 gram Carbon needed
• For C:N Ratio 12:1 = 12 x 20 = 240 gram Carbon needed
• For C:N Ratio 15:1 = 15 x 20 = 300 gram Carbon needed (add 615gm sugar or 1230gm molasses)

Notes: 

• It’s already proved that C:N Ratio 10:1 and 15:1 are more successful than others
• Never add Carbohydrates all at a time, it may reduce the DO level
• Maintaining 20:1 Ratio will require more Carbohydrates that will add more cost to your project

 

How to Control Ammonia when C:N Ratio is 15:1

• 8 ppm Ammonia 10,000L Water = Add 2 Kg 460gm Sugar & Double for Molasses
• 4 ppm Ammonia 10,000L Water = Add 1 Kg 230gm Sugar & Double for Molasses
• 2 ppm Ammonia 10,000L Water = Add 615gm Sugar & Double for Molasses
• 1 ppm Ammonia 10,000L Water = Add 300gm Sugar & Double for Molasses
• 0.5 ppm Ammonia 10,000L Water = Add 200gm Sugar & Double for Molasses
• 0.03gm Sugar or 0.06gm Molasses required to manage 1ppm of Ammonia in 1 Liter Water
• 0.45gm Sugar or 0.90gm Molasses required to manage 1ppm of Ammonia in 15 Liter Water
• 1.74gm Sugar or 3.48gm Molasses required to manage 1ppm of Ammonia in 58 Liter Water

 

Final Words

BIOFloc system can be successful if you understand how to control Ammonia using an appropriate Carbon Nitrogen Ratio (CN Ratio). Its technology-based farming, failure of maintaining single criteria can create havoc in the BIOFloc System. Before you start your own BIOFloc Fish Farming, understand what is BIOFloc and how it works.