Aquarium controller

This aquarium controller manages the following devices, and measures the following parameters:

- Water temperature (measure of value, control of heater and cooling fan (proportional PID);

- Measure of ambient temperature;

- Light: ON-OFF of power supply, PWM dimming, sunrise and sunset simulation (2 outputs);

- Measure of CO2 circuit pressure;

- CO2: ON-OFF of solenoid valve at setted times, cutoff if overpressure

- ON-OFF of air pump at setted times

- Fertilization: two dosing pumps controlled to dosed quantity and choice frequency (days at week);

The circuit was assembled on PCB and all PCB files are provided, but it can also assembled with modules linked by wires.

The controller is powered by a 12Vdc 2A power supply, because the fan and the peristaltic pump I used, need 12Vdc. Arduino Nano board operate at 5V, and voltage is regulated by a step down DC-DC converter installed on the main PCB board. The timing is based on a DS3231M RTC.

The AC devices (heater, solenoid valve, lights, aerator) are controlled by SSR and Triac.The temperature sensors are DS18B20 in waterproof stainless steel case.

The eather and the cooling fan are non controlled in ON-OFF mode, but like a proportional PID. The advantage obtained is a better regulation of the temperature. All other AC devices are operated in ON-OFF by solid state relays G3MC-202P-DC5

The fan and the peristaltic pumps are powered by a 7-ch NMOS array low-side driver TPL7407LADR, that is similar to the ULN2003A, but more efficent ad low drop out voltage. Some NMOS are paralleled for increase the current capability.

All informations are showed on a 2004 LCD with I2C interface, and all settings are operate by 5 tactile swithes on a separate PCB board.