Introduction: Aquaponics in Hanoi Growing Shrimps and Safe Vegetables Without Soil, Powered by Solar Energy
OOPS published by error, and I did not find a way to put it in draft again.... Sorry.
This project provides a simple solution for small scale hydroponics and aquaponics. This means safe vegetables, no soil nor dirt and virtually no polution. The first stage second stage is a simple system with electric control, a battery and a pump. The second stage delivers for the same system a simple disaster prevention automation including messaging and switches to take action.
Wherever I move to, I start with low ambitions for my window sill or Balcony. But over a short time span my balcony becomes the one green spot in the building. This project grew from the need to make a hot balcony a place where vegetables and some fish in a tank thrive, instead of getting shriveled or cooked by the heath. Also because where I live now soil and dirt seems not to work in the long term for potting plants: organic matter disappears fast, the need for constant watering compacts the soil and roots don't thrive.
The initial project answered to 3 needs:
- To get rid of the problematic potting soil. The hot and wet climate the plants must be watered twice daily, and the soil organic matter degrades very fast.
- Aerate and filter the water for the fish
- Water cascading bringing quality of life for me, my fish and my plants.
This project has 5 chapters:
- Justs building the system
- Choice of fish or crayfish
- Making choices about the plumbing: dimensions, substrate, sump tank, etc....
- Electricity: power from the sun, pumping and aerating.
- Nutrition balances.
The arduino automatisation is an add-on, mostly about intervening when things go wrong, but also delivers data for the heck of it. it will be in a separate instructable.
- If the pump stops working, and plants get dry because the water getting short, a message is send to the owner.
- If the tanks gets too hot for the fish, adding more water flow and oxygen (and a message is send)
- If the system is somewhere clogged or there is a leak and the pump risks to run dry, stopping the pump and send a message.
- Electrical conductivity, as a proxy measure for ammonia and ammonium,
So the collected data are:
- temperature in the fish tank, as an indicator for oxygen availability, oxygen sensors are expensive. Too hot leads to continuous pumping and adding an air pump. Too cold during daytime the same Cooling?
- water level in the pump tank: too low: stop the pump.
- //water level/humidity in one of the planting areas: message if low: indicates blockage or faulty pump.
- Electric conductivity
This extension has 3 steps too:
- choosing and connecting the sensors
- relays, pumps and airpumps
- sending data
Step 1: Aquaponics With Hanoi Wild Fresh Water Shrimp (Macrobrachium Nipponense, Oriental River Shrimp)
Proof of concept: a working micro-aquaponics system on a balcony in Hanoi, providing safe and abudant vegetables, herbs and animal protein.
In this step we chose the manure & meat producing livestock.. The options around Hanoi are diverse, however, the limitations are severe for micro-systems. As I work on a Balcony system, I tried to limit the total weight to 200 kg. The standard reference work for the region is the FAO publication "Small-scale aquaponic food production".
Traditional fish culture around Hanoi is done in ponds that are fertilised with cow, pig or poultry manure, with additional fish feed depending on the aspirations of the farmer. The fish is adapted to the seasonal cycle, with very hot summers and low oxygen in the ponds, and cold winters, down to 12-13 degrees C: Ponds are often covered with duckweed, to limit the growth of filamentous green algae, that can cause sudden blooms killing all fish.
In the upper layer there is a carp feeding in that space: the silver carp (Hypophthalmichthys molitrix)In the middle zone, there common carp (Cyprinus carpio), Mud carp (Cirrhinus molitorella) in the lower area Eastern River Shrimp (Macrobrachius nipponense). In other systems, the flooded rice paddies are stocked with Shrimps (Macrobrachium lancasterii) or prawns and harvested later in the season. It is clear the setup uses optimally all layers of the pond, and the system is very efficient in food use, as most of the carp are herbivores, and the shrimp feed on the micro-organisms living from detritus.
Moreover, goldfish and Koi are bred for their ornamental value, and can be used in aquaponics systems. In the more commercial systems, with export objectives, the main species are the giant river prawn (Macrobracium rosenberghii), catfish and tilapia. Moroever the Walking Perch is grown successfully in
For a system with a water tank of only 60-120 liters, the options are very limited: fingerlings of godlfish or other fish that are sold before reaching maturity, or the Wild fresh water shrimp. According to the literature a fish tank for goldfish should only have 1-3 fish for 60-100 liters. A literature review reveals that this shrimp moslty acts like the Giant Freshwater Prawn. I refer mostly to two overview documents, the article in thuysanvietnam, and the reference book "freshwater river prawns, biology and farming". Moreover, there is ample litterature from China, although often without tranlation beyond google transpate. There are a few differences between the oriental reiver shrimp and the giant river prawn, making the shrimp more adapted to (micro-small scale) aquaculture: Although the shrimp is not exported, it is the first or second species for aquaculture in China. The taste is said to be superior. There are traditional health benefits too. In Vietnam too, the price per kg is for the wild shrimp than for the tiger prawn or the giant prawn. In general, smaller animals are more efficient in food conversion and multiplication.The shrimps and prawns are territorial, however, due to the small size, the nipponense can be accomodating by building "apartments" 1-1.5 " PVC tubes of 10-15 cm long. In small tanks, the number of Giant prawns would fast be limited to 1 or 2.The shrimps have their full life cylce in fresh water. No need for buying larvae, nor feeding them special food, if there is enough plankton in the water.The shrimps survive the cold winters of Hanoi, although they stop breeding once the water temperature drops below 21-23 degrees C.The shrimp is reputed to be more resistant to most pests and diseases. Although due to its size, especially when in the larval stage, they can be eaten by other species.The could probably be fed only kitchen scraps or Black Soldier Fly waste.As the pincers of the shrimps are less deadly, co-habitation with fish should be more feasible (to be researched).Stocking the system, hard lessons learned: The official research services focus on the export products. So I did not have access to broodstock, larvae, nor specialised feed. Mortality of freshly aquired shrimps: However, on the wet markets around the city, these shrimps are sold alive, at least early in the morning. The literature warns for the high mortality when obtaining these shrimps, mostly due to broken legs and pincer. This is compounded by the fact that in Hanoi, the marketers scissor off the leggs just before selling them, as these legs are kind of wiry and not look tasty. So the buying should happen early in the morning, and only un-scissored shrimps. Ammonium spikes increasing the mortality: So when stocking the system without enough precautions, the shrimps release a lot of ammonia, especially when there is mortality. This ammonia must be eliminated fast, otherwise the whole batch will die. Elimination happens by an aerobic process, producing nitrite (also poisonous for fish and shrimp) and transforming the nitrite to nitrate, with way less toxicity. This means the flow must be fast enough and the biological activity of the system must be well established. I had an instance where the water ammonia content spiked to 8ppm from near 0 in less than an hour. A killer approach: minimal setup. Most of the problmes I encountered were due to going unproven for the bottom of the investments: tanks small, system very small, tubes clogging with algae, not . Currnt situations Conclusion: The basic rules of aquaponics are very much true:
Overdimension every aspect of the system: tubes, pumps, water in the system, flow ratio.You need enough water in the system to delute any sudden problem, so the ratio tank/resst of the system of 1/1 seems indeed mininal, with hindsight. I added some volume to the system: a sump tank, more trays with hydroculture.This water must flow fast enough, otherwise your buffer makes no difference.Don't even think about using available trasnparent tubes. The growth of algae will clog it very fast. Do use always a size wider than on first thought.Whatever they say, I experienced that cycling is necessary, otherwise the stocking should really happen slowly and step by step.More advanced: As shit can happen really fast, having an automated system of sensors that can ring an alarm are very usefull:
Electric conductivity is a proxy for ppm ammonia. it is cheap and works up to now.Water temperature: as I started the system too late, and would love to have still somebreeding, I will keep the system at 22-23 degrees.Flow measureRelay to switch on an additional pump or airpump if disaster strikes.
Step 2: Making Choices: Flood and Drain? Compost Tea? Where to Place the Pump?
My balcony system is just for fun, so some of the choices made are not for people who really depend on it. Moreover the initial motivation was rather about getting my ornamental fish a happier life than vegetal or animal production. However, with my background of bio-engineer, reading the instructables and manuals, I encountered a set of "practices" where the discussions were rather how to do them than why we do them. Of some of these elaborated practices I found little or no research or even trials confirming the need to do them. As Snape wrote in his potion book: "Just shove a bezoar down their throats.".
Bell siphons, flood and drain, at least 30 cm growth medium, pipes and constant flow
How deep the system?
In a garden, most plants root only in the upper layers, 10 -20 cm at the most. In the Nutrient Film technique, the plants grow in just a constant trickle of water. The amount of nutrient rich water available to the plants seemst to be the deciding factor. How deeper the system, how more weight, more water, more things that can go very wrong, with neighbours complaining too. The most important argument for deeper systems seems to be the need to have weighty grow medium keeping older, bigger plants in place. This however could be solved by placing meshed wiring in the medium low in the wet zone, anchored in place (with a brick or to the side of the system). One reference.
The more professional systems use just constant water flow in pipes. For all plants. This negates most arguments in favour of deep beds. However, while trying to save on electricity, I limited too much the flow at a certain point, and the vegetables suffered. The aerobic system can only be maintained if there is enough flow.
Flood and drain
The theory behind flood and drain is quite elaborate, but also questionable. This kind of theoretic underpinning should be proven by empirical research. Most research I found, shows little or no advantage of a flood and drain system. One of the problems seems to be the development of anaerobic zones with a deeper zone with stagnant water. However, in some literature I found the management of such zones as one of the few ways to assure enough iron availability. On the other hand such zones could cause denitrification (nitrogen lost as N2 gas).
It seems to me there is a good case to make to have a nice wet aerobic zone in the medium, that is not too often disturbed. This can be arranged by choosing a growth medium with a good wicking capacity of at least 10 cm. Expanded clay and cocos should do the trick. Gravel and sand less, and these are very heavy too (but cheap). Anaerobic denitrification and production of toxins seems to be a major issue, although there too I found little or no research beyond anecdotal stories.
So I ended up with part in 20 cm grow beds, with expanded clay, a shallow top layer dry, some 10 cm with water wicked up, and some 5 cm with water. I only recently found worms to add, I will keep you posted on their development. By making this choice, I don't need a sump tank that might bring the building down with its weight.
A second part of the system are 12 cm PVC plumbing with holes for plants of 5.2 cm. A sieve is at the end of each fo the 10 cm tubes, before the water flows to a lower level. I filled up to the water level with expanded clay, to increase the bio-filter capacity. This proved necessary. The flow is 50 minutes on, 10 minutes off, at more or less 60 l/h, the content of the fish tank.
Compost tea and nutrition
It was clear from early on that my red mollies are not producing enough nutrition. The first symptoms were Iron shortage, but also Nitrogen shortage. A google search quest was started.
I wanted to come up with a solution, meaning a continuous system needing only regular maintenance. Any feeding system that works in a discontinuous way is not automatisation.
Most aquaponics users seem to use compost tea: stable, ready compost, preferably vermicompost, that is put in a bucket with constant aeration. The liquid from this bucket is used or bought as compost tea. The explanation says the constant aeration is needed because anaerobic bacteria could produce toxins or denitrification.However, under strong aerobic pressure, the mineralization (freeing of nutrients) of the compost would also produce a liquid that is going stronger and stronger therefore difficult to use. It seems in more traditional systems, they just put compost in regular intervals between the plants in a sieve. Moreover the only scientific material on compost tea I found called the advantages of compost tea above leachate a myth.
Compost is the end product of decomposition of organic material and normally it has a stable C:N ratio of between 8 and 15. It decomposes further, and when mixed with soil, normally half of the Nitrogen is freed over a crop (more when hot & wet and aerobic). It seems a waste to abandon this smooth process and create a complicated additional compost tea factory instead.
As my system pumps every hour for 15 minutes, the water in my pump bucket lowers some 10 cm, because it takes time for all the water to flow back. I took a fine sieve I filled with compost and placed it on top of the pump bucket. This compost gets drained every 15 minutes and is wet the rest of the time. I adapt the quantity of compost to get nice dark green veggies.
pH, CEC, Ammonia, Nitrite, nitrate
I measured all these elements in the beginning, and except for the lack of N-fertilizer, everything seemed to be fine and stable.
However, once I moved to a more intensive system (more shrimps, more water flow) the Ammonia measurement seems very necessary, and in need of constant monitoring. As the ammonia and ammonium ppm is very tightly linked to the Electrical Conductivity, and a EC sensor is cheap, I installed this.
Where goes the pump
The water flows 100 % with gravity down, no tricks no engineering, no flood and drain, just an overflow pipe. The veggies on top, down to the second veggie bed, flowing into the highest fish tank to the lowest fish tank to the pumping bucket.
I chose not to pump from the fish tank, but from an overflow pump bucket, for if something blocks somewhere, there will still be water in every recipient with living things.
Plumbing: PVC rules.
I started with a "rustic" mindset, and put with silicon some bamboo pipes in my fish tanks. A mistake. The bamboo rots and the pipe is riskily narrow. For the other pipes I used stadard pvc pipes, nicely overdimensiond. Just make a round hole in the plastic and screw the pipe on it, it works. For the hose from the pump to the top, very important is tnot tto use transparant piping. Otherwise algae growth clogs the system.
My plants grow in a layer of expanded clay of some 15-20 cm. The bottom 4-5 cm are underwater, providing also a safety period for the system of 1-2 days in the case of a total breakdown. The next layer is more or less 10 cm wicked water in the medium, and there is a top layer of a few cm that is dry.
The second part of the system is PVC tubes of 12 cm with regular holes for the vegetables, and added expanded clay for improving the biofiltration.
I have 5 levels, and one pump. The water flows by gravity alone to the bottom where it is pumped up again. Apart from the pump, it are just pipes from top to bottom, no valvehighest are 2 growing beds, followed by 2 fish tanks and the pumping bucket. In the pumping bucket is a sieve with compost to provide extra fertilisation.
Step 3: Electricity: Power From the Sun, Batteries, Timing, Pumping and Aerating.
The starting point was that I wanted an autonomous system. Solar powered.
In Hanoi, Vietnam this is not that easy: the solar power components for small systems are not readily available, and there is not a lot of sun most of the year. I started with some ready - bought amazon solar water pump. However, this was clearly not dependable enough for the variable weather (lots of clouds) of Hanoi.
Low energy - higher energy systems: with systems that have only a very low voltage (6v) and low energy needs, a system using just a few schottky diodes and a set of lithium batteries works fine. The solar panel will not grill the battery nor the motor. The best instructions I found here: http://www.robotroom.com/Solar-Recharging.html
However, once you want something more reliable, with more power, the electronic protection of your battery and your system must be more elaborated.
I chose to go for a 12V system, as there are sufficient instruments using this voltage, and it is capable to give enough power to pump to a certain height.
So you just buy:
- A solar panel that is at least double the size you calculate to need (I first went for 12W, after a week without sun I moved to 30W)
- A regulator (cheap and 10A will do): the regulator protects the battery from too much power and from completely getting completely drained. This is necessary for lead-acid, still the cheapest for systems where the weight is not so important. The regulator must be connected first to the (charged) battery, so it feels whether it is 6, 12 or 24 volts. Than you connect the solar panel and the charge.
- A battery (12 V) Motorbike batteries are good at giving bursts of energy, slow, constant release battery is better.
- A pump capable of lifting the water high enough (watch out, the pumps offered often lift only 0.90 m or less), and the pump should pump more or less the volume of your fish tank through the system once every few hours. When I tested it showed 15 minutes per hour would suffice.
- A clock switch on 12V (check! the voltage for operating the clock is the one to check. The switch is normally up to 240V). I programmed it so it would switch on for 15 minutes every hour.
See the attached shopping list.
It seems so simple now, but once you have all these, you just connect them and it works. (see photos).
Step 4: Internet of Things: Sensors for Real Time Monitoring and Control of Water Quality and Pumping
I will make a seperate instructable for this part