---
created: 2026-05-26 21:42
modified: 2026-05-26 21:42
type: note
tags:
  - gardening
  - ESP32
  - airponics
  - aquaponics
aliases: []
---
# [[Aquaponic towers]]

## 1. Lighting Strategy & Specifications

To optimize costs and plant growth, the system uses two distinct lighting tiers: high-intensity bare LED strips for fruiting zones (peppers, strawberries) and cheap, raw floodlights for leafy green zones (lettuce, herbs).

### Fruiting Zone: Custom Programmable LED Strips
* **Core Philosophy:** Bypasses commercial retail markup by using high-efficiency, multi-channel bare boards.
* **Component Title to Search:** `Samsung LM281B+ quantum LED strip 50cm 48V 3 channel` [1]
* **Target Listing Reference:** *AliExpress Item 1005006814849161 (10pc 50cm PCB Board Combo pack)*
* **Spectrum (Kelvin) & Wavelengths:** Combined Warm White (3000K), Cool White (5000K-6500K), Far Red (660nm), and UV/IR [1].
* **True Wattage:** ~26W per 50cm strip (~260W total power draw per 10-pack).
* **Target Metric:** Delivers a Daily Light Integral (DLI) of 20–30+ required for fruiting.

### Leafy Green Zone: Commercial Utility Floodlights
* **Core Philosophy:** Zero-branding, raw industrial illumination.
* **Component Title to Search:** `200W LED Floodlight IP66 Waterproof 6500K Daylight`
* **Target Listing Reference:** *AliExpress Item 1005008430067364*
* **Spectrum (Kelvin):** 6500K (Daylight Blue). This specific spectrum prevents leafy greens from getting tall, leggy, and weak.
* **True Wattage:** Marketed as 200W, but typical actual wall draw is **40W to 70W** due to standard Driver-on-Board (DOB) efficiency configurations. This lower draw is ideal for keeping power costs down.


## 2. Power & Electrical Infrastructure

Because raw PCBs are used, the power supply must be decoupled from the wet zone.

[ 240V AC Wall Out ] ──> [ MeanWell LRS-350-48 ] ──> 48V DC ──> [ ESP32 Mosfet Shield ] ──> LED Strips

### Power Supply Unit (PSU) Specifications
* **Type:** Industrial Constant Voltage Enclosed Switching Power Supply.
* **Recommended Model:** `MeanWell LRS-350-48` (48V DC, 7.3A, 350W output).
* **Safety Protocol:** Mount the PSU entirely outside the greenhouse or wet environment. Run only safe, low-voltage 48V DC lines into the tower area.

### Wiring Configuration
* **LED Strips:** Wire the 48V strips in **parallel** across the main DC bus lines to maintain a constant 48V voltage drop across every single board.
* **Wire Gauge:** Use minimum **18 AWG** stranded copper wire with silicone insulation to handle the DC current loads without voltage drops over distance.

---

## 3. Thermal Management & Mechanical Mounting

Bare LED strips will overheat and self-destruct within days if run without passive thermal management.

### Heatsink Requirements
* **Material:** Structural architectural Aluminium U-channels, structural T-slot framing (2020/2040 profile), or dedicated `500mm LED strip aluminium radiator profiles`.
* **Thermal Interface:** Secure the bare PCBs to the aluminium using **thermally conductive double-sided tape** or thin thermal paste combined with mechanical nylon clips. 
* **Tower Orientation:** 
  * Connect 3 to 4 strips end-to-end vertically to create 1.5m to 2m rigid columns.
  * Position 2 to 3 of these structural columns around the perimeter of the tower, facing inward at a distance of **30cm to 45cm** from the plant canopy.

### Environmental Moisture Proofing
* **The Hazard:** Falling, splashing water from the vertical aquaponic flow creates a high-humidity environment.
* **Mitigation:** After soldering your DC lines to the PCB pads, coat all exposed copper pads, solder joints, and wire connections in **marine-grade conformal coating** or **liquid electrical tape**.

---

## 4. ESP32 Control & Automation System

An ESP32 cluster governs the lights dynamically to simulate natural cycles and minimize winter electricity consumption.

┌─── Low-Side N-Channel MOSFET (White Channel)  
├─── Low-Side N-Channel MOSFET (Red Channel)  
[ ESP32 Logic Pins ] ─┼─── Low-Side N-Channel MOSFET (Blue Channel)  
└─── 0-10V DAC PWM Circuit (For dimmable external drivers)

### Light Dimming & Spectrum Control
* **Hardware Interface:** Connect the ESP32 GPIO pins to a multi-channel **Logic-Level N-Channel MOSFET shield** (e.g., IRLZ44N). The MOSFETs handle the high-voltage 48V switching via low-side PWM switching.
* **Dynamic Control Loop:** Integrate a digital light sensor (such as a `BH1750 Ambient Light Sensor`) inside the greenhouse. Program the ESP32 to track natural winter sunlight and dynamically scale back the LED duty cycle during bright hours, maximizing power savings.
* **Fruiting Logic:** Programmatically bias the PWM output to scale down the Red channel during initial vegetative growth, then ramp up the Red channel to 100% capacity as the plants hit flowering age.

---

## 5. Root Zone Thermal Management

In winter greenhouse production, cold root zones lock up plant metabolism regardless of how much light is provided.

* **The Problem:** Air temperature can drop safely to 15°C, but if the water hitting the bare roots drops below 18°C, the plants stop absorbing phosphorus, iron, and nitrogen.
* **The Target Temperature:** Strictly maintain the nutrient mist/water between **18°C and 21°C**.
* **The Solution:** Insulate the main nutrient storage reservoir with foam wrap. Place a submersible **aquarium heater** directly inside the water tank. 
* **Automation Hook:** Interface a waterproof `DS18B20 temperature sensor probe` inside the root chamber and tank. Wire it to the ESP32 to trigger a solid-state relay driving the heater, ensuring the root core stays warm efficiently without wasting money heating the ambient air.