An aquaponics unit is effectively a larger aquarium where there are both fishes and plants. The only difference here is that the plants and fishes do not co-habitat. They are grown separately but the water they are growing is recycled between them. Basically, the fish excreta filled water is provided to the plants. The feces have high nutrient value. The fish poop lumps are broken down by friendly bacteria in the fish tank. It is important to break down the fish waste as it is toxic in that form. The plants use these broken down fish waste into nutrient solution for their growth. In turn, the fresh and purified water is sent back into the fish tank again.
The big question – Aquaponics system
Here comes the biggest doubt whether or not to use extra nutrients for the benefit of the plants. The direct answer would be NO. there is no need to add extra nutrients in the growing medium. The nutrients coming from the fish pond is really rich in nitrates and other macro nutrients. But there will be time when the nutrients may not be enough for the plants and at that time add in only a minimal quantity. But do not add it on regular basis. In case the plants don’t use up these nutrients, it is not healthy for the fishes. The best option would be to use supplementary nutrients that suit the growth stage of the plants.
The starting point
The initial months of an aquaponics system will have only minimal nutrient availability from the fish pond. During that time it is better to grow those plants that do not need higher nutrient contents. Plants like lettuce and other green salad varieties would be a good choice. The reason behind this choosy plant growing is that there is a bio-filter attached in the aquaponics unit that filters the water from the fish tank. This bio filter has those useful bacteria that convert the fish waste into usable form. These bacteria need to establish themselves to have a full time filtering done. Once the full time conversion starts the bacteria will be able to provide high amount of available nutrients for the plants. The nutrients that are available now would be able to support the growth of high nutrient demanding plants like tomatoes and cucumber.
Quality of the fish feed matters
It is said that the fish that are fed with high quality feed produces top quality waste. Sound totally weird but true. A balanced diet in fish will produce the fish waste that has most of the useful nutrients for the plants. Under these circumstances where the fish gets a balanced diet, the resulting fish waste will have the necessary nutrition and there is no need to add extra into the water.
pH is essential
The pH of the water in the fish tank and that in the plant growing system are different. As the fish uses the feed and metabolizes the pH of the water drops gradually. In that case the plant system requires a pH up in the form of potassium and calcium based buffer system. Since these are useful for the plants any deficiency of these nutrients is compensated, preventing any use of a supplementary addition.
What is lacking?
Fish feed does not have iron in it. so naturally the waste also will not have that mineral. Since this mineral is essential for the chlorophyll content of the plant leaves, add a little of it into the hydroponics system, once a week. Aquaponics is the most effective way of recycling the water and to avoid the use of external nutrients. The fish waste is utilized for good purpose and reduces the environmental impact. Almost 90% of the water can be recycled many times. The nutrients are used by the plants to have fresh water for the fishes and they support the plants by providing the growth nutrients. this is the best artificially created natural environment that benefits us humans also.
Nutrient Deficiency in Aquaponics
Nutrient deficient plants are prone to be a victim of insects because of their low immunity power. Can you fight a bunch of honeybees swarming towards you that too when you are not even healthy? Same is the issue with your plants. Low immunity power will only deteriorate your plants health and the end results are just ‘quite poor’. Just like us, plant need different diet.
There are two types of nutrients – mobile and immobile nutrients. The former move in the plant such as moving from old leaves to new ones and motivate them to grow, a nutrient deficient plant will show symptoms in older leaves first. The latter, however, nutrients cannot move once they are used for plant growth. Basically it means that the plants doesn’t get the necessary nutrients, the symptoms will show in the newer leaves first and start to wither off or just won’t grow. This is because the old leaves still have their immobile nutrients in themselves and are insufficient in providing new supply for the leaves.
Some of the mobile nutrients include potassium, chloride, nitrogen, phosphorus, molybdenum etc. while immobile includes iron, calcium, copper, zinc, sulfur, manganese, boron etc.
Two of the common issues in Aquaponics seen are chlorosis and nitrogen toxicity. Interveinal chlorosis occurs when there is high iron content in the nutrients. Make sure to check your pH levels. Aim for a pH of 6.8 as more than 7.0 can make it difficult for the plants to consume efficiently.
When the leaves turn to deep green or black color, then its a sign of nitrogen toxicity. It can even disrupt the fruits. This means that your fishes are producing high levels of nitrogen than plants can handle. The best method is to add good amount of plants and stop feeding your fishes for two days so as to balance off the nitrogen levels.
Adding nutrients in Home and Commercial Aquaponics system
When you are addressing nutrient deficiencies in aquaponics such as fighting off tormenting rodents in the garden, make sure that the nutrients you are adding to your plants do not prove detrimental to your fishes. Here are top five all natural non-toxic plant fertilizers that work great on your plants as well as your fishes.
1. Fish poop
Not many know but one of the prominent source of nitrogen is in fish poop. It is primarily used in many modern day fertilizers because of its huge functionalities in delivering benefits to all living cells that starts from metabolism to photosynthesis. In fact, it is an inevitable part of chlorophyll that is vital for photosynthesis.
2. Steamed bone meal
Animal bones or bones of shellfish comes with excellent calcium, phosphorus that are food for your plants. They also have a dominant role in photosynthesis and helps in conversion of solar energy to chemical energy that is necessary for maturity of plants, root growth, blooming phase and many. Bone meal can also help in balancing the pH level in the system.
3. Bat poop
Bat poop comes with high level of phosphorus, potassium in greater amounts that are very much necessary for your plants. It is one of the building blocks of protein not to mention promote proper photosynthesis. Simply sprinkle this 100% natural fertilizer to get healthy yields.
4. Maxicrop plus iron
A natural non-pollutant product, Maxicrop plus iron is made out of fresh growing seeweed that is delivered to you in a complete soluble form. With little amounts of NPK and other minerals such as iron, zinc etc. maxicrop can be fed as per the pH balance, climatic conditions and water temperature.
5. Balanced pH
This might not be a fertilizer but maintaining a great level of pH measure is one of the important aspects when it comes to growing plants in aquaponics. The ideal range of pH for nitrogen is slightly alkaline (7.0-9.0) while for micronutrient availability is lightly acidic (5.5-6.5). Lower levels of pH can hinder the detoxifying process of ammonia to nitrate to nitrate. The best stable point of pH is 6.8 to 7.0 to maintain healthy plants and fish simultaneously.