This guide documents the process i followed when designing my Deep Water Culture hydroponics system. The system can be scaled as needed – certain parts scales better with eg. 3-4 basins per airpump.
Prerequisites / Materials
Basins
- Height: Depends on the plant and how big root net they grow. Overall, I’ve been using 17cm boxes
- Type: Depending on size the basin will easily need to carry 20kg+ of water, I’ve used reinforced boxes where the bottom is supported
- Light: To prevent algae growth minimal light should be allowed through the plastic. The less light the longer between water changes are needed.
- Maintenance: I’d suggest going with a brand / type of box that can also be acquired in the future if you want to replace or extand the system
- Lids: Matching lids are a must, to ensure a close fit and minimal light intrusion.
Suggestions: Auer Packaging 60x40x17 – reinforced bottom remember to purchase matching lid as well.
Basin preparation
Each basin needs a steady constant supply of air to prevent root rot. The lid of the basin can be optimized to match the size requirements of the produce, eg. lettuce requires more horizontal space than spring onions. In addition, lettuce also requires a bigger base to grow from and thus the growth media/basket should be bigger. The lid must be drilled to match the chosen configuration, eg. 2×4 rows, 5cm basket (remember to measure exact basket size to allow the lip to rest on the lid)
Net baskets
As mentioned above, choosing a basket depends on the produce.
Suggestions:
- 50mm Gro-Lys.dk – Drill size 48mm
- ??mm Amazon.de – Drill size ?? (these match common off-the-shelf hydroponics systems)
Growth media
A number of different growth media can be used, some allows for direct seeding, others don’t. It’s a matter of cost versus workload. Common for all types are that the bottom of the media needs to make contact with the water.
- Leca Clay pebbles
- Peat
- Coconut Coir
- Rockwool
Leca Clay Pebbles
- Reusable: Yes, clean in hot water and maybe a bit of citric acid for cleaning lime deposits
- Seeding: No, the seed must be seeded in another media, however it can be transplanted after the plant has reached a good size. For transplanting grown plants this is a very easy and reusable media to use.
- How: Seed in eg. a small rockwool plug, and surround with Leca pebbles in the basket
- Difficulty: Medium, pebbles and basket needs cleaning and combining pebbles and rockwool takes some time when filling basket
- Tested products: Plagron Euro Pebbles – very clean product, pH neutral, no minirals
- Gro-Lys.dk
- Price per basket: Reusable, but requires seedling or another growth media
Peat
- Reusable: No, in addition it is far from sustainable
- Seeding: Direct
- How: Use a plug that matches the size of the basket, let it soak for a few minutes in the basin and simply add the seed on top of the plug. Note that some seem to contain minirals and should be “washed” before use – dip in water and squeeze dry a couple of times.
- Difficulty: Easy, only basket needs cleaning
- Tested products: Non-brand. There are many avaiable in different sizes.
- Amazon.de
- Price per basket: 2.5DKR)
Coconut Coir (with mesh)
- Reusable: No, however they are compostable and could even be repurposed for potted plants or in the garden
- Seeding: Direct
- How: Use a plug that matches the width of the basket, let it soak for a few minutes in the basin, the plug will expand vertically, and simply add the seed on top of the plug.
- Difficulty: Easy, only basket needs cleaning
- Tested products: Non-brand, many are available, just make sure size fits and they have a mesh
- Amazon.de
- Price per basket: 1.0DKR)
- Basket: 50mm
- NOTE: I only just moved to testing this media, so far it seems to be my preferred
Rockwool
- Reusable: No, goes to landfill…
- Seeding: Direct
- How: Couple of options, either use a plug that matches the size of the basket or use a smaller plug and surround with leca pebbles. The last option allows for more reusability and gives some stability to the growing plants
- Difficulty: Medium, pebbles and basket needs cleaning and combining pebbles and rockwool takes some time when filling basket
- Tested products: Grodan Rockwool Tray
- Gro-Lys.dk
- Price per basket: 0.8DKR + reusable leca pebbles
- Basket: eg. 50mm
Aeration
The water need a constant supply of air to prevent root rot. If the pump stops for an extended period of time, the produce will rot. Aquarium pumps are good for this purpose and can often be found with splitters to allow for multiple air stones to support multiple basins.
Suggestions:
- AQQA, Amazon.de Variable, select 15W version. Can be a bit noisy but good throughput and allows for 4 basins.
- Hailea, Amazon.de Not tested yet, have it as backup in case a pump stops working. Somewhat more noisy
Lights
While plants do require different light spectrums during their different growth phases, for ease of use full-spectrum LEDs are recommended, they have low power consumption and can support all growth stages.
Also note that the light requirement changes during the growth so either use dimmable lights or use a flexible system for suspending the lights and changing the distance.
Suggestions:
- LEDLife Max-Grow, mrperfect.dk choose to match the width of your basins, eg. 3 x 40cm wide basins could be covered by a 120cm light – but with it being 60cm deep 2 next to each other would be recommended
Measuring Equipment
Test sticks should be plenty, make sure they cover the basics, pH, pollutants etc. Optionally a full online, live test system can be used for each basin
Suggestions:
- Test sticks?
- Tuya based, automated, Aliexpress.com Measures a lot of metrics
- Manual, amazon.de
Setup
Describe how to wire and control everything… …
Seeding
Certain plants prefer to sprout in darkness where others prefer light. But common is they all require relatively high humidity. To allow for this, use a lid either transparent or blackout. Refer to instructions for the seeds.
Lids
Add Fusion 360 design file / STL
Growing
During the different growth phases a number of requirements change. As the plant grows larger it will need more fertilizer (and different potentially), different lights and use more water.
Fertilizer
Specific fertilizer intended for hydroponics exist, easily dissolvable in water and easy to dose. There are many to choose from, but I’ve only tested one brand so far – Big Plant Science (DK Company), Combine Big Calcium with Big Bloom or Big Grow. Account for 2 parts Big Calcium, 1 part Big Bloom per liter of water every week on average. This is a very basic starting fertilizer and lots of additional types can be added to support the different growth stages. For short lived produce, it should be just fine.
The nutritional requirement for different plants can be found and matched against a TDS – Total Dissolved Solids measurement, this allows for adjustments and preventing over or under fertilizing.
Suggestions:
- Direct, bigplantscience.com Big Bloom + Big Calcium
- Reseller, gro-lys.dk
pH Levels
Also depending on the plant, the pH level of the water should be kept at a certain level. Most plants thrive around a pH of 6.5, use a pH modifier to reach the required level. Use test strips or automated equipment to measure.
Suggestions:
Fertilizer dispenser
As fertilizer needs to be added manually every week to each basin, the process of dispensing correct amounts can make it a lot easier.
Manual
Use a squeeze wash bottle and fill into a measurement beaker.
Suggestions:
HyGrow Dispenser
I’m currently designing an automated dispensing system… check back later 🙂
Workflow / Schedule
| Step | Task Description | Notes |
|---|---|---|
| 1 | Prepare the basins | Follow setup instructions, validate air pumps etc. working (Assuming basin is clean |
| 2 | Fill basins with water | Use clean water. |
| 3 | Add growth media | Use appropriate media for your plants |
| 4 | Mix and add fertilizer | Follow the recommended ratios. Optionally pH-balance the water |
| 5 | Place plants or seeds in media | Ensure roots or bottom of growth media are in contact with water |
| 6 | Check water levels | Refill when necessary |
| 7 | Harvest and maintain | Clean and prepare for next cycle. When harvesting replace growth media and re-seed |