What is this new type of experiment?
From the sources that I read about hyrdoponics, aeration was important for the plants to get enough air. It also prevents bacteria and algae from growing, which is the same reason why we can drink flowing water but not still water. In the first method I did, which is the Kratky method, there is no aeration. However, the kratky method is designed to be a disposable method: you can grow one plant, then use new water. With the new method, you can plant new plants without changing the water too often; around 2 or 3 times a year(this really depends on how many plants are being grown, how well cleaned the tank was at the start, how much exposure the water gets to light, and many other things). This means that this method is more water efficient.
Why did I do this experiment?
I wanted to learn more about hydroponics. I wanted to make sure that the things I learn about hydroponics were not just abstract knowledge, and instead knowledge that I can apply and actually grow plants. This method also can teach me new things and make me learn new things on the way. I also think it’s easier to remember knowledge about hyrdoponics by doing the experiment myself.
The second method is considered to be a natural progression in hydroponics. Kratky method is the simplest form and this is the second simplest form. This method is better considering that it is more water efficient, hence more eco-friendly.
The Build Process
Preparation of Materials
A plastic box(around 60cm long, 30cm wide, 25cm deep), hyrdoponics fertilizer A and B, 2 plastic netty pots*, pH guage, pH balancing powder, airpump, airstone, plant growing lights, foam board(big enough to fit the box, approximately 5cm thick), hydrogen peroxide, clay balls, kale seeds, lettuce seeds, measuring cup, gloves, knife, rag
*I used plastic food strainers because I didn’t have access to real netty pots
Step 1 – Put the bottom part of the box on the foam, draw the outline of the box, cut the foam along that line.
This method includes putting in a foam that holds the plants. The foam should fit in the box, be able to float freely but also block out as much light as possible. That’s why we measure the very bottom of the box, instead of the top or the middle part because the box tapers down so the foam would get stuck as the water level reduces if the measurements were taken from any other parts of the box.
Step 2 – Lay down the netty pots on the foam that you have already cut, draw the outline, cut the foam with around 2cm less in diameter than the netty pots.
If the netty pots taper down, it should be the wider side of the netty pots, like mine. The aim here is for the netty pots to sit in the holes but not forced through. The bottom of the pots should touch the water and the water should not reach the top of the clay balls. There should at least be a 2cm gap between the top of the clay balls and the water. This is to allow the roots to breathe.
Step 3 – Cut a hole in the foam
This is for the pipe of the air pump to go through the foam easily without being squeezed or interfering with the foam’s ability to float.
Step 4 – Clean the foam, box, pipe of the air pump
Use hydrogen peroxide. Get a rag, apply a mixture of water and hydrogen peroxide, and clean EVERYTHING thoroughly. This is to prevent bacteria build up in the water. Although it’s common for some algae to build up in hydroponic systems, severe algae buildup can lead to oxygen and nutrient deprivation and unsuitable pH levels. Common algaes found in hydroponics are Chlorophyta, Streptohyta, Spirotaenia, Charphytal, Mesostigmatophyceae, Phaeophyceae, Black Algae, Red Algae(this one is the most dangerous in aquaponics, because this one can kill fish), The most important thing to do to prevent algae buildup is to keep the water away from the light. However, making sure everything is clean and clear of pathogens and bacteria helps to prevent it too.
Step 5 – Measure the water you will put in and add fertilizer accordingly
The water should be at least 15cm deep. I decided to use 18L of water. The fertilizers for aquaponics tell how much of it you need based on the water you use. Mine requires 50mL per 20L, so I used 45mL of both fertilizer A and B. Hydroponic fertilizer solutions are a mixed blend of nitrogen, phosphorus, potassium, magnesium, and sulfur as well as very low concentrations of copper, boron, iron, manganese, molybdenum, and zinc. These are all nutrients which plants need and would be found naturally in high quality soil. However, in intensive farming many of these nutrients are deficient in soil hence why farmers also fertilize their fields for better yields.
Step 6 – Measure and control the pH to 5.5~6
Use the pH testing kit, measure the pH, and use the pH powder to either increase and decrease the pH level. Lower pH may inhibit plant growth by influencing the structure and breakdown of organic substances that benefit your plant, reduce your plant’s water uptake, in some plants inhibit CO2 assimilation, and cause oxidative stress and electrolyte leakage. too high pH can prevent nutrient uptake and lead to deficiency. For example, iron deficiency causes pale or yellow leaves in young plants while calcium deficiency will lead to leaf cupping and tip burn.
Step 7 – Put the stone of the air pump in the tub
Attach the airpump hose to the air pump and the other end to the air stone. Then, put the stone in the middle of the box. Remember the air pump is not waterproof so it should stay outside the box. Aerating the water helps the plants breathe through the roots and it keeps the water oxygenated preventing algae.
Step 8 – Place the foam on top of the water
Place it so that the hose of the air pump is in the hole we made in step 3. Ensure that the foam is floating freely. If it’s catching on the air pump hose, side to the box, or anything else you need to trim the foam down.
Step 9 – Put clay balls in the netty pots and wash them
Put enough clay balls in the netty pots to come level with the top surface of the foam. This is to create and air gap between the water and the top of the clay balls so that the seeds and top of the roots do not come directly in contact with the water because they need to breathe. You should wash the clay balls to clean off dust or other materials.
Step 10 – Put the netty pots in the holes that we made in the foam
It should fit so that the pots touch the water and the foam can properly hold the pots. If the hole is too small, you can trim some parts off to help them fit.
Step 11 – Set up the lights
Set up the plant-growing lights so that the plants get enough light. It should have some time where it doesn’t get light, just like night, so use a timed light or manually turn them off every 12 hours.
Step 12 – Plant the seeds
Plant 4 kale seeds in one pot and 4 lettuce seeds in the other. Put something on top of the netty pots to block the lights for the first few days before the seeds sprout. This is because many seed varieties only sprout when they are just below the surface and grow up seeking light.
Step 13 – Water from the top
For the first few days at least, scoup a little water and fertilizer mixture from the tub and water the seedlings from the top until the roots touch the water.