Indoor aquaponics is excellent for growing your organic produce and farmed fish at home all year round. But can you have an aquaponic system in an apartment with limited space, and how is it run?
The rest of this article will discuss the topics essential to indoor aquaponics:
- What is indoor aquaponics?
- Can aquaponics be done indoors?
- The easiest indoor aquaponic system
- Components required for a small indoor aquaponics system
- Materials and steps to build an indoor aquaponics system
- Best plants to grow in indoor aquaponics systems
- Indoor aquaponics fish stocking ideas
- Balancing your indoor aquaponics system
- Number of plants for an indoor aquaponics system
- Amount of food produced with a small indoor aquaponics system
- How big can indoor aquaponic systems be?
- Do I need to supplement my indoor aquaponics system?
- Indoor aquaponics daily and weekly maintenance
- Considerations before getting an indoor aquaponics system
- Why the small indoor aquaponics system does not need a mechanical filter
What is indoor aquaponics?
Indoor aquaponics is a closed-loop growing system involving fish and plants that is small enough to be placed indoors. Fish waste containing water is pumped into a grow bed that acts as a biological filter. Nitrifying bacteria that sit on the growing media and worms convert the fish waste into nutrients used by plants for their growth. The purified water is then directed back into the fish tank, and the cycle starts over again.
Can aquaponics be done indoors?
Yes, aquaponics can be done indoors. Depending on the available space, indoor aquaponic systems usually have a smaller scale than outdoor or greenhouse aquaponic systems implying smaller yields. Although smaller-sized, they are fun to build, operate, and contribute to a lively and calm ambiance.
The easiest indoor aquaponic system
Indoor aquaponics works just like outside aquaponics. The real differentiator is the scale of the aquaponics system and which components are built into it. Usually, indoor aquaponics systems are smaller and have fewer components to fit into living rooms, garages, and basements.
While there is much information on more elaborate systems that, for example, include sump tanks, mechanical and biological filters, small indoor aquaponic systems, and grow beds including bell siphons, indoor aquaponic systems focus on the most critical aspect: Growing plants by using fish waste.
A small timed ebb and flow system is the easiest for indoor aquaponics. It consists of a fish tank, a grow bed, a water pump, and an overflow.
Water is pushed by a timed water pump (pump without backflow preventer) from the fish tank through a delivery pipe into the grow bed, raising the water level in the grow bed. As soon as the pump turns off, water flows from the grow bed back through the delivery pipe (which now acts as a drain) and through the pump into the fish tank. An overflow sets the maximum water level within the media bed.
In terms of its size, this small ebb and flow system can be placed in a shelving unit that can hold the weight of the water-filled fish tank, media-filled grow bed, and the grow light. Of course, if you have more space available, you can expand your system by adding a second grow bed, a sump tank, a radial flow filter, or a biological filter.
Components required for a small indoor aquaponics system
These are the components required for a small ebb and flow indoor aquaponics system:
- Shelving unit
- Fish tank or aquarium
- Tub for the media bed
- Clay pebbles
- Fish tank light
- Grow light
- Water pump
- Air pump
- Pipes and tubes
Materials and steps to build an indoor aquaponics system
Look at the materials and steps for building an indoor aquaponics system with a 30 gallon (114 liters) fish tank and a proportionally sized grow bed. I assume that the aquaponics system is placed into a 3-shelf storage shelving unit.
Materials
- Heavy-duty storage shelving unit (dimensions about 14″ D x 36″ W x 54″ H)
- 30-gallon aquarium (dimensions about 13.5″ D x 31″ W x 19″ H)
- 20-gallon tub (dimensions about 13.5″ D x 31″ W x 12″ H)
- 16 gallons of clay pebbles
- LED Fish tank light
- LED Grow light (usually come with hanging cords and carabiners)
- Extension socket
- Mechanical timer outlet
- Submersible aquarium water pump (without backflow preventer) with a 3/8 inch tubing outlet that can turn over the aquarium water volume three to four times per hour
- Submersible aquarium air pump
- One piece 3/8 inch vinyl tubing (length depending on your shelf build/planned setup)
- 1/2 inch threaded male to 3/8 inch barb connector (barb on one end and 1/2 inch threaded fitting on the other end)
- 1/2 inch threaded slip connector (threaded on one end and slip on the other end)
- Two 1/2 inch pipes (length depending on your shelf build/planned setup)
- 1/2 inch ball valve socket
- Two 1/2 inch uniseals
- 6-inch pipe (about 14-inch length)
- 6-inch pipe cap
- 1.25-inch hole saw
- Pipe saw
- Steel or wood saw (depending on the shelf material)
- Silicone grease
- PVC glue / solvent cement
- Fish, red wiggler worms, and plants to populate the indoor aquaponics system
Steps to constructing the indoor aquaponics system
- Place the fish tank on the lower shelf of the shelving unit
- The next step is drilling two holes into the plastic tub; make sure you use the correct hole saw size. The easiest way for checking is to put the backend diameter of the uniseal against your hole saw and to make sure that it is nearly the same
- Drill two holes close to each other in the center of the box that will hold the media with the 1.25-inch hole saw
- Put the two unseals into each of the holes from the inside respectively (they should be snug)
- Put some silicone grease on the inner edges of the uniseals to make the 1/2-inch pipes slide through easier
- Preparation of the shelf
- Depending on where you like the delivery and drain of the grow bed, saw a round hole with a diameter of about 6 inches into the middle of the upper shelf (this will be the hole through which the delivery and drain will go).
- Installation of the pump
- Put the 3/8 inch vinyl tubing on the pump.
- Put the 3/8 barb fitting into the vinyl tubing.
- The barb fitting goes onto the threaded 1/2 inch fitting.
- Installation of the delivery and drain pipe:
- For the delivery and drain pipe, estimate at which height you like the valve to be. The valve should be above the fish tank and under the upper shelf for easy access. The one end of the delivery and drain pipe should be very slightly above the uniseal.
- Saw up the first 1/2 inch pipe where you want the valve to be.
- Slide the upper half of the 1/2 inch pipe through the first uniseal until its upper end is slightly above the uniseal
- Then connect the two 1/2 inch pipe pieces to the 1/2 inch ball valve socket.
- Installation of the overflow pipe:
- For the overflow pipe, estimate the maximum water level within the media bed. As a general rule of thumb, the media should be at a maximum of 4/5 of the height of the edges of the media bed. The overflow pipe’s maximum water level and end should be 1 to 2 inches below the media surface to minimize algae growth.
- As we are building an ebb and flow system, the water level within the fish tank will fluctuate. To reduce any noises of inflowing water, the bottom of the overflow pipe should be below the minimum water level of the fish tank.
- Installation of the media guard:
- For creating the inlets of the media guard, we saw out linear gaps on the 6-inch pipe. More precisely, draw a line around the tube at the height of 4 inches from the bottom of the pipe. Within 4 inches, draw about seven evenly spaced lines with a length of 2 inches each on each side of the tube. As a result, you should have 14 lines facing each other.
- Sew along the 14 lines for creating the inlets.
- Drill two to three holes into the 6-inch pipe cap. This will ensure that there won’t be any vacuum building up once the system is operational.
- Place the 6-inch pipe with the inlets facing down around the delivery and the overflow and glue (PVC solvent cement) the bottom end of the pipe to the bottom of the grow bed.
- Place the 6-inch pipe cap on the 6-inch pipe piece (media guard).
- Placing the grow bed on the shelf and connecting the delivery/drain pipe to the pump:
- Place the grow bed on the upper shelf of the shelving unit with the delivery/drain pipe and the overflow pipe going through the sawed-out hole.
- For the delivery/drain, connect the lower 1/2 inch pipe-end to the 1/2 inch threaded slip connector. Ideally, the lower 1/2 inch pipe should end within the lower third of the fish tank.
- Press the pump against the inside back aquarium wall to stay put.
Setting the water cycle
- Fill up the fish tank to about 3/4 of its height with water. We will install the air and water pumps, test if everything is working as supposed, and ensure no leaks.
- Place the air pump into the fish tank and plug it into a wall socket. I recommend using an extension socket that is zip-tied to the frame of the shelving unit at the height of about 20 to 30 inches. This way, you reduce the risk of water spilling on any power connections causing a short circuit. The air pump should be running 24/7.
- The air pump should be working now and air bubbles should rise to the water surface within the fish tank.
- Place the aquarium light at the edge of the fish tank and plug it into the extension socket. As most aquarium lights have a built-in-timer, set the timer to your desired day and night cycle.
- Plugin the water pump into the mechanical timer outlet. Plugin the mechanical timer outlet into the extension socket.
- Set the mechanical timer so that it runs every hour for 15 minutes. Each hour has four prongs equivalent to 15 minutes on the mechanical timer. Push every fourth prong inwards so that you have the following cycles. Total daily cycling time should be 12-14 hours:
- On-cycle: 15 minutes
- Off-cycle: 45 minutes
- Total daily cycling time: 12-14 hours
- For testing the water pump, it is best to use the switch on the side of the mechanical timer. Turn it on to make the pump start working. The grow bed should now begin to fill with water. After filling above overflow level, the water should flow back into the fish tank. Make sure that the piping does not have any leaks.
- Now that everything is working, you can switch off the water pump. Use the valve to ensure that the water level rises to the maximum height of the overflow within 15 minutes (without overflowing). You can again use the switch on the side of the mechanical timer and time it with your watch or use the timer on your phone.
Setting up the LED growing lighting cycle
- Assemble the LED light following the instructions of the manufacturer.
- Hang up the LED grow light at the bottom of the very top shelf of the shelving unit. As grow lights operate optimally at certain heights above the plants, adjust the hanging cords to the proper height as specified by the manufacturer. The grow lights should be approximately 6 to 12 inches above the plants.
- Plug the LED light into the extension socket.
- Most LED lights have controls for setting the on- and off-cycles. The LED lights should be set to the following day/night differential:
- On-cycle: 12-14 hours
- Off-cycle: 10-12 hours
- The total daily time when the light is on: 12-14 hours
Putting in the media and starting the aquaponic cycle
- Rinse the clay pebbles thoroughly and fill them into the media bed. The media should be at a maximum of 4/5 of the height of the edges of the media bed
- The clay might be floating once the grow bed is flooded. Give it a couple of days to soak up the water, and the pebbles will settle.
- For starting the nitrogen cycle in the system, add an ammonia source and old fish feed to the fish tank and let it cycle for a few days. This will lead nitrifying bacteria to colonize the grow beds and thus increase nutrition levels.
- Use a test kit for checking the nutrition levels in the water. The test kit should allow for testing pH, Ammonia, Nitrite, and Nitrate. Through regular testing, you can track how the cycling of your aquaponics system.
- Check the pH level. Make sure that it is between 6.0 and 6.5. If the pH is above 6.5, carefully apply fish-safe pH lowering solution (below 6.0 fish-safe pH raising solution) and let it run a couple of cycles through the entire system. Measure again and repeat if necessary.
- Once your aquaponic system cycles properly, place the fish carefully into the tank. Make sure that the fish can acclimate to the water in the tank. For example, put the fish in their retaining plastic bag into the new tank and wait until the water temperature is adapted.
- As you have a brand new system, the nitrifying cycle still is developing, and nutrition levels are low. Carefully plant only several plants as nutrition levels are low at this stage.
- Also, note that you may have to change the water frequently in the beginning as the purifying and nitrifying capacity is building up over time.
Placing the fish into the water
- Before placing the fish into the water, you should ensure that the air pump runs and test the water quality using a special test kit. The test kit should allow for testing the pH, Ammonia, Nitrite, and Nitrate levels.
- Once you have checked the water quality, it will be safe to place the fish into the tank. The fish needs to acclimate to the water temperature and the water quality in the aquarium. Therefore, put the fish in their retaining plastic bag into the new tank and wait until the water temperature is adapted. Then slowly mix in some water from the aquarium into the water in the plastic bag.
- Once the temperature and water quality in the plastic bag are adapted, releasing the fish into the fish tank is safe.
- I recommend discussing your aquaponic plans with your local fish dealer or fish hatchery. They also may have additional advice for you for keeping the fish.
Starting aquaponic plants from seed
From my perspective, the best method to start plants in a home aquaponics system from seed is to use peat pellets. Peat pellets are dehydrated peat wrapped by a non-woven, biodegradable fabric. They provide a good structure for the plant’s roots to grow in and are easy to transplant.
- Put the peat pellet into warm water to make the pellets swell.
- Once they are swollen and cooled off, pull back the top netting slightly and put in the plant seeds.
- Put the planted peat pellet into the clay pebble media until it just hits the maximum water level.
- The plant seeds will germinate between 5 to 10 days.
Starting aquaponic plants from seedlings
You can also start aquaponic plants from seedlings:
- Give the roots a good rinse so that the earth is well removed. You want to handle the seedlings carefully as the roots are very vulnerable.
- You can stick a piece of pipe into the media bed and dig a little hole. Place the plant about two to three inches deep into the hole, pull out the pipe, and backfill any unevenness with surrounding clay pebbles.
- The plant will adapt to the environment and eventually grow in the media bed.
Best plants to grow in indoor aquaponics systems
As indoor aquaponics systems are smaller in scale, robust plants requiring low nutrient levels and a reasonable amount of space are best suited.
Smaller-sized aquaponics systems have fewer fish, less fish waste, smaller biological filters, and thus have lower nutrient levels. Therefore, leafy greens and herbs that have low nutrient demand are best suited for indoor aquaponics:
- Asian mustard green (Mizuna)
- Arugula
- Basil
- Chives
- Collard greens
- Kale
- Lettuce
- Mint
- Microgreens
- Mustard greens
- Bok choi
- Spinach
- Swiss chard
- Tatsoi
- Tokyo bekana
- Watercress
While leafy greens and herbs strive in indoor aquaponics systems, larger fruiting vegetables tend to do worse. They may overwhelm the indoor aquaponics system as they demand a more significant amount of nutrients and space:
- Beans
- Broccoli
- Cabbage
- Cucumbers
- Peas
- Peppers
- Strawberries
- Squash
- Tomatoes
To decide which plants to put into your system, you should regularly check the nutrition levels in the water by using a test kit that allows for testing pH, Ammonia, Nitrite, and Nitrate levels. Based on regular testing of the water quality parameters, you can get a good feeling for the number and the type of plants that fit your system.
Indoor aquaponics fish stocking ideas
Because of the limited fish tank size, filter capacity, and room temperature, fish species that a small indoor aquaponics system can hold are mainly limited to the following species:
- Goldfish (Carassius Auratus): 68°F to 74°F (20°C to 24°C)
- Silver perch (Bidyanus Bidyanus): 73ºF to 83ºF (23°C to 28°C)
- Jade perch (Scrotum Barcoo): 75ºF to 80ºF (24°C to 27°C)
If you plan to build a more extensive indoor aquaponic system, you could additionally consider the following species:
- Tilapia (Cyprinus Carpio): 70ºF to 85ºF (21°C to 29°C)
- Barramundi / Asian Sea Bass (Lates Calcarifer): 77°F to 86°F (25°C to 30°C)
- Koi (Cyprinus Carpio): 65°F and 75°F (18°C to 24°C)
The water temperature will adapt to room temperature depending on where you place your aquaponics system indoors. When thinking about the fish stocking for your indoor aquaponics system, remember that each fish species has a different range of preferred water temperatures.
Balancing your indoor aquaponics system
Generally, aquaponic systems should balance fish, plants, and filtering capacity (nitrifying bacteria). As indoor aquaponic systems have smaller fish-tank sizes and filtering capabilities, they should be over-filtered and understocked.
In more detail, here is how many fish and plants an indoor aquaponics system with a 13.5 x 31 x 12 inch grow bed, and a 30-gallon aquarium can hold considering the filtering capacity and the aquarium water volume of an aquaponics system:
Filtering capacity and fish stocking density
As a general rule of thumb, one square foot of a media bed with a minimum depth of 12 inches (31 cm) has the filtering capacity to hold 1 lb (0.5 kg) of fish. This means that a small aquaponics system with a 13.5 x 31 x 12 inch grow bed equating to 2.9 square feet can hold up to 2.9 lbs (0.9 kgs) of fish.
As the easiest indoor aquaponics system does not have a mechanical water filter that filters out fish waste solids, it is wise to keep the stocking density below one and thus below 2.9 lbs (0.9 kgs) of fish. If the stocking ratio is below 1, a separate mechanical filter for solid fish waste is unnecessary as long as there is an even water distribution and red wiggler worms are in the media bed.
Aquarium water volume and fish stocking density
The maximum fish stocking density is limited by the filtering capacity and the water volume within the aquarium. Generally, one inch of fish needs one gallon of water, with the first fish requiring the double amount.
Following this rule, the 30-gallon fish tank of the easy indoor aquaponics system could hold 29 inches of fish.
Indoor aquaponics fish stocking density
Applying both rules of thumb for filtering capacity and water volume gives you the fish stocking density of your indoor aquaponics system. The following table shows the full-size length, weight, number, and maximum fish for a small aquaponic system with a 30-gallon fish tank and a 13.5 x 31 x 12-inch media bed for some of the most popular fish species for aquaponics.
As you can see, a small aquaponics system with a 30-gallon fish tank and one 13.5 x 31 x 12-inch media bed can only hold 4 Goldfish:
| Fish species | Length (Full size) | Weight (Full size) | Max. number |
| Tilapia (Cyprinus carpio) | 24 in (60 cm) | 11 lb (5kg) | 0 |
| Silver perch (Bidyanus bidyanus) | 15.8 in (40 cm) | 3.3 lb (1.5 kg) | 0 |
| Jade perch (Scrotum barcoo) | 15.8 in (40 cm) | 4 lb (1.8 kg) | 0 |
| Barramundi / Asian Sea Bass (Lates calcarifer) | 59 in (150 cm) | 6.6 lb (3 kg) | 0 |
| Goldfish (Carassius auratus) | 6 in (15 cm) | 0.5 lb (0.2 kg) | 4 |
| Koi (Cyprinus carpio) | 25 in (120 cm) | 10 lb (4.5 kg) | 0 |
Of course, if you are interested in harvesting edible fish before reaching full size, you could also keep other fish such as Silver Perch or Jade Perch. Remember, removing one fish from the aquarium would mean that the cycle needs to be restarted once fingerlings are reintroduced.
Also, more fish species options are possible if you plan to build a more extensive indoor aquaponics system with a larger fish tank and more filtering capacity.
Number of plants for an indoor aquaponics system
The number of plants that an indoor aquaponics system can hold is a balancing game as it depends on nutrient concentration and growing conditions.
Nutrient levels depend on the number of fish, quality of fish feed, and filtering capacity:
- Fish waste available for the nitrification process (based on the total weight of the fish that live in the system)
- Amount, quality, and type of fish feed
- Filtering capacity (based on the total area that nitrifying bacteria can colonize)
- Application of nutrient supplements
Growing conditions mainly depend on:
- Space available for the plants in the grow beds
- Light exposure (either from daylight or grow lights)
- Other environmental factors such as air temperature and airflow
From my experience, sufficient spacing of plants is a good starting point for finding the number of plants for your indoor aquaponics system:
- Lettuce (medium size): 4 to 6 in in-row and 12 in between rows
- Leafy greens such as kale, collard, bok choi, and mustard (small size): 6 to 8 in in-row and 12 to 18 in between rows
- Leafy greens such as kale, collard, bok choi, and mustard (large plants): 12 to 24 in in-row and 30 to 36 in between rows
A small indoor aquaponics system with a 30-gallon fish tank and a 13.5 x 31 x 12-inch media bed could hold about 4 to 6 lettuce heads or six leafy greens. However, besides sufficient spacing, you should closely monitor nutrients and pH levels by testing the water quality.
Amount of food produced with a small indoor aquaponics system
A small indoor aquaponics system with a 30-gallon fish tank and a 13.5 x 31 x 12-inch media bed can hold about 4 to 6 lettuce heads or six leafy greens.
Lettuce takes about 30 to 45 days to grow from germination to maturity. If you plant six seedlings into the grow bed, you can expect 4 to 6 lettuce heads or 4 to 10 lbs of lettuce per month.
If you choose to plant bok choi, you can place about six seedlings into the media bed that can be harvested after 30 to 45 days. This would give you a yield of 6 bok choi plants or 6 to 8 lbs of bok choi per month.
The best yield is often achieved by combining different plant species with varying growing cycles, nutrient demands, and spacing requirements. If you have a more extensive home aquaponics system, you can, of course, produce larger food quantities.
How big can indoor aquaponic systems be?
In theory, indoor aquaponics systems can be as large as one could imagine. However, in reality, larger-scale commercially-run aquaponic farms have an average size of 0.03 acres (1,300 sq. ft.), while the world’s largest aquaponic operation stretches across 3.70 acres (160,000 sq. ft.). Factors like available indoor space, necessary investment, and operating costs, available sources of revenue and sales outlets, as well as technical challenges and complexity of large scale aquaponics, represent a limit for indoor aquaponics systems:
Available indoor space
The main limiting factor for the size of an aquaponic system is the available indoor space. The more space is available, the larger an indoor aquaponics system can be:
- Small ornamental aquaponics systems easily fit on a tabletop or a sideboard.
- An indoor aquaponics system in a storage shelving unit fits a normal-sized living room, basement, or garage.
- More extensive indoor aquaponics systems that include, for example, sump tanks and mechanical and biological filters may fit into larger basements or garages.
- A commercial size indoor aquaponic farm can fill a warehouse-sized greenhouse.
Necessary investment and operating costs
Large indoor aquaponic farms require extensive funding for capital investment mostly related to building the system:
- Facility
- Aquaponics system and components
- Labor (initial setup)
- Machinery and equipment
Once operational, indoor aquaponics systems require regular maintenance translating into a flurry of operating costs:
- Labor (maintenance, logistics, sales)
- Electricity
- Water
- Seed and seedbed
- Feed
- Supplements
- Machinery and equipment (running costs)
- Land rental (if not purchased)
As you can see, building and operating a large-scale aquaponics system is a capital-intensive endeavor, imposing a natural limit to the maximum size of indoor aquaponics systems.
Sources of revenue and sales outlets
While extensive investment is necessary to set up and run a large-scale indoor aquaponics system, agricultural produce and services are the primary sources of revenue for large-scale commercial aquaponic farms:
- Selling crops
- Selling fish
- Aquaponics classes
- Consulting
Aquaponics plants and fish can be sold through the following outlets, usually close to the aquaponic farm.
- Farmers markets
- Farm stands
- Community-supported agriculture
- Grocery stores
- Restaurants
- Institutions
- Wholesalers
Larger-scale commercially-run aquaponic farms require large and professional sales operations to market the aquaponic produce, while customers are usually in a close geographical radius. Limited sales opportunities lead to smaller-scale indoor aquaponics systems.
Technical challenges and complexity
Apart from space, investment, and revenue generation opportunities, another limiting factor for the size of indoor aquaponic systems is technical challenges and interdisciplinary complexity:
- With the size of the aquaponics system, technical complexity increases. Extensive indoor aquaponics systems are designed and optimized to a given scale to deal with technical complexity.
- As commercial aquaponics involves many disciplines such as aquatic and plant-related biology, biochemistry, biotechnology, measurements, control technologies, finance, economics, and marketing, interdisciplinary complexity increases with the size of the indoor aquaponics system.
Do I need to supplement my indoor aquaponics system?
As aquaponics systems often lack certain nutrient elements, supplements should be added for optimum plant growth. Generally, seaweed-based and fish-safe fertilizers are used in aquaponics. Which nutrients are missing can be identified with the help of self-done water quality test kits and more elaborate water quality tests processed by laboratories.
Plants need several nutrients to strive. These nutrients can be subdivided into primary, secondary nutrients, and micronutrients.
Primary plant nutrients:
- Nitrogen (N)
- Phosphorous (P)
- Potassium (K)
Secondary plant nutrients:
- Calcium (Ca)
- Magnesium (Mg)
- Sulfur (S)
Micronutrients:
- Iron (Fe)
- Copper (Cu)
- Zink (Z)
- Manganese (Mn)
- Boron (B)
- Molybdenum (Mo)
- Fluoride (HF)
While Nitrogen (N), Phosphorous (P), and Sulfur (S) are generally well available, aquaponics systems often lack Potassium (P), Calcium (Ca), and Magnesium (Mg). Moreover, micronutrients such as Iron (Fe) and Magnesium (Mg) are necessary for plants to process available nutrients. Generally, nutrient elements should be closely monitored and added if they are below recommended levels for optimum plant growth.
Potassium can be added as Potassium Bicarbonate, while Calcium can be added as Calcium Hydroxide. As supplements such as Potassium and Calcium raise the water pH level, you should closely monitor pH levels to be in a stable range between 6.5 and 6.8.
Iron can be added in the form of DTPA Iron Chelate to the grow bed. Again, the exact amounts depend on the iron levels within the water that can be tested using an iron water test kit. The adding frequency is about once per month.
Magnesium can be added as Magnesium Sulfate (Epsom Salts). Magnesium levels are harder to test, and therefore the exact amounts necessary to be added are based on personal estimates. Magnesium should be added about every two weeks. Magnesium can also be directly sprayed on the plants for a foliar feed.
For boosting micronutrients, a seaweed-based kelp additive is best suited to providing a wide range of plant nutrients. The kelp additive should be added about every two weeks.
If you are an aquaponics beginner and the indoor aquaponics system is your first project, consider nutrient supplementation as something to keep in mind and as optional.
Indoor aquaponics daily and weekly maintenance
To keep your small indoor aquaponics system running smoothly, a few maintenance tasks should be carried out on a daily and weekly basis. These tasks take about 5 to 10 minutes per day and 20 minutes per week:
Fish and fish tank maintenance
| Activity | Frequency |
| Feed your fish high-quality fish feed | Daily |
| Feed the fish | Daily or twice a day (depending on the water temperature and recommended feeding rate) |
| See if the fish are eating all the food (if not, scoop out the rest of the fish food with a net) | Daily |
| See if the fish are healthy and do not have any blemishes | Daily |
| See if the air pump is running constantly | Daily |
| See if the water pump is working according to the set schedule | Daily |
| Pull out the water pump and see if it is working properly and not clogged up | Monthly |
Grow bed maintenance
| Activity | Frequency |
| See if the grow light is running as scheduled | Daily |
| Check for plant pests | Daily |
| Pick any dead leaves of the plants | Daily |
| Pick up any leaves that are lying on the ground of the grow bed (avoid pests like Mildew and Mold) | Daily |
| Check whether any fish waste is accumulating in the grow beds | Weekly |
| Check the delivery, drain, and overflow for any clogging (roots can grow into the pipes, clay pebbles can clog the drain) | Weekly |
Water testing
| Activity | Frequency |
| Check if the pH is within the desired range | Daily |
| Check if the water temperature is within the desired range | Daily |
| Perform an ammonia, nitrite, and nitrate test with a freshwater test kit (take water from the fish tank) | Weekly |
Considerations before getting an indoor aquaponics system
Some thoughts are vital if you consider getting an aquaponic system for your home. Thinking about the following points beforehand will ensure that the setup and running of your indoor aquaponics system will be a fun experience:
Indoor aquaponics systems have grow lights
As the indoor aquaponics system might be standing in your living room or bedroom, you want to consider that the grow light needs to be running between 10 to 14 hours a day. This can become uncomfortable depending on the placement of the aquaponic system, your daily routines, and your sleeping habits. Selecting an optimal place or getting a cover or grow tent for the light and the grow bed can reduce light exposure.
Indoor aquaponics systems are noisy
Aquaponics tends to be noisy due to working pumps and flowing water. Choosing the location for your indoor aquaponics system wisely will make your daily life easier. Also, it is recommendable to get the noise level to a minimum by using quiet aquaristics pumps and selecting a calm aquaponics design and setup.
Amount of food produced
If you plan to get an indoor aquaponics system to grow food, you should consider the available space as the real limiting factor. A small indoor aquaponics system with a 30-gallon fish tank and a 13.5 x 31 x 12-inch media bed can grow about 4 to 6 lettuce heads or 4 to 10 lbs of lettuce per month. Larger systems can, of course, lead to higher yields.
Avoid potential safety hazards
Aquaponics involves using water and electricity (for pumps and lights) simultaneously, implying a potential safety hazard. Therefore, to prevent any short circuit or fire hazard, consider the placement of the electrical wiring above the floor and water level. Also, make sure to plumb and seal water holding pipes or tubes properly.
Get in touch with your landlord
If you rent your place and you are unsure whether running an indoor aquaponics system is permitted, contacting your landlord and discussing your indoor aquaponics plans before starting is a good idea to avoid any disputes.
Overall, you want to ensure that your indoor aquaponics system does not constrain your daily life and is safe to operate.
Why the small indoor aquaponics system does not need a mechanical filter
You may wonder why the DIY small flood and drain system does not include a separate mechanical filter for handling solid fish waste aside from the media-filled grow bed.
Although some members of the aquaponics community insist on the necessity of mechanical filter components for all aquaponics systems, there is no biological or technical need for a filter within a small-scale indoor aquaponics system as long as the system meets the following aspects:
- Use of high-quality fish food
- Excess fish food is scooped out of the fish tank after feeding the fish (use a net)
- Worms are added to the grow bed that break down solid fish waste
- Water is evenly distributed in the grow bed
- The stocking density is below one (grow bed filtering capacity vs. total fish weight)
The takeaway
The beauty of indoor aquaponics is that you can have a fully working aquaponics system without worrying about environmental conditions. A small indoor aquaponics system is easy to build, maintain, and budget friendly.
Indoor aquaponics is suitable for aquaponics enthusiasts with different experience levels and is well suited for beginners.
Remember not to overstock the fish tank and keep an excess headroom in terms of filtering capacity through the media beds, which essentially are biofilters for the system. Regular water testing is key to ensuring that your fish stay healthy and the indoor aquaponics system is well balanced.
Your indoor aquaponics system will make a great addition to your home with good planning and maintenance.
