Hydroponics grows plants in nutrient-rich water instead of soil, and automating the nutrient dosing process with peristaltic pumps and Arduino eliminates the tedious manual mixing and ensures your plants receive consistent nutrition. This guide shows you how to build an automated hydroponics dosing system that monitors pH and TDS levels and dispenses nutrient solutions automatically.
Hydroponics Nutrient Basics
Plants need three things from hydroponic nutrient solution: the right concentration (measured by TDS or EC), the right pH (5.5-6.5 for most plants), and the right nutrient ratio. When the plant absorbs nutrients, TDS drops. As pH drifts, nutrient availability changes. Automated dosing keeps both parameters in the optimal range.
System Design
The system consists of:
- A reservoir with the hydroponic nutrient solution
- pH and TDS sensors immersed in the reservoir
- 3-4 peristaltic pumps for different solutions (Nutrient A, Nutrient B, pH Up, pH Down)
- Arduino reading sensors and controlling pumps via relay modules
- OLED display showing current readings and dosing status
Components List
- Arduino Mega (more analog pins for sensors)
- 3-4x peristaltic pumps (12V)
- 4-channel relay module
- TDS/EC sensor module
- pH sensor module with BNC connector
- 12V 5A power supply
- 0.96″ OLED display (I2C)
- Silicone tubing (matching pump specs)
- Nutrient solutions (A, B) and pH Up/Down
Peristaltic Pump Setup
Mount pumps above the reservoir to prevent siphoning. Label each pump clearly:
- Pump 1: Nutrient A solution
- Pump 2: Nutrient B solution
- Pump 3: pH Down (acid)
- Pump 4: pH Up (base)
Calibrate each pump by measuring actual ml dispensed per second of operation. This calibration factor is used in the dosing code for accurate dispensing.
pH and TDS Monitoring
Read sensors at regular intervals (every 5-10 minutes) rather than continuously. After dosing, wait 2-3 minutes for the solution to mix before reading again to avoid oscillation.
Auto-Dosing Code
// Hydroponics Auto-Dosing System
const int PUMP_NUTA = 2, PUMP_NUTB = 3;
const int PUMP_PH_DOWN = 4, PUMP_PH_UP = 5;
const int TDS_PIN = A0, PH_PIN = A1;
float targetTDS = 800; // ppm
float targetpH = 6.0;
float tdsMargin = 50; // Dose if below target-margin
float phMargin = 0.3;
float mlPerSecond = 0.5; // Calibrate your pump!
unsigned long lastDose = 0;
unsigned long doseInterval = 300000; // 5 minutes
void pumpML(int pumpPin, float ml) {
float seconds = ml / mlPerSecond;
digitalWrite(pumpPin, LOW); // Relay active low
delay((int)(seconds * 1000));
digitalWrite(pumpPin, HIGH);
}
float readTDS() {
int raw = analogRead(TDS_PIN);
float voltage = raw * 5.0 / 1024.0;
return voltage * 500; // Simplified; calibrate with standard solution
}
float readpH() {
int raw = analogRead(PH_PIN);
float voltage = raw * 5.0 / 1024.0;
return 3.5 * voltage; // Simplified; calibrate with buffer solutions
}
void setup() {
int pumps[] = {PUMP_NUTA, PUMP_NUTB, PUMP_PH_DOWN, PUMP_PH_UP};
for (int p : pumps) { pinMode(p, OUTPUT); digitalWrite(p, HIGH); }
Serial.begin(9600);
}
void loop() {
if (millis() - lastDose > doseInterval) {
float tds = readTDS();
float ph = readpH();
Serial.print("TDS:"); Serial.print(tds);
Serial.print(" pH:"); Serial.println(ph);
if (tds targetpH + phMargin) {
pumpML(PUMP_PH_DOWN, 0.5);
Serial.println("Dosed pH Down");
} else if (ph < targetpH - phMargin) {
pumpML(PUMP_PH_UP, 0.5);
Serial.println("Dosed pH Up");
}
lastDose = millis();
}
}
Frequently Asked Questions
How often should the system dose nutrients?
Check every 15-30 minutes but only dose if readings are outside the target range. After dosing, wait at least 5 minutes for mixing before the next reading. Over-dosing is worse than under-dosing — always dose in small increments.
Can I use submersible pumps instead of peristaltic?
Submersible pumps lack the precision needed for dosing. Even 0.5ml too much pH Down can crash your pH. Peristaltic pumps give precise, repeatable volumes based on run time. Always use peristaltic for nutrient dosing.
How do I calibrate pH and TDS sensors?
Use buffer solutions (pH 4.0 and 7.0 for pH, 500 ppm standard for TDS). Immerse the sensor, record the analog reading, and calculate the conversion factor. Recalibrate monthly for accuracy.
Conclusion
An automated hydroponics dosing system combines peristaltic pump precision with sensor feedback for hands-off plant nutrition management. Start with TDS-based nutrient dosing, add pH control, and expand to WiFi monitoring with ESP32 for remote garden management. This project is particularly relevant in India where urban farming and terrace gardening are growing rapidly.
Shop pumps and sensors at Zbotic.in.
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