Automatically controlled Aquarium/Terrarium.

Description

For aquarium/terrarium size of: 40x25x30 cm

I created this project to make the basic maintenance of my aquarium automatic.  

I am using an Arduino nano to measure and control the temperature inside the aquarium and to measure time and automatically set the airing, RGBW LEDs and filtration on or off. To display and control the Arduino I choose to use an 16x2 LCD display and a rotatory encoder.

To keep track of time, I count the periods from the AC line via an optocoupler. This works even in the long term, as there is a system for correcting frequency fluctuations in the European power grid. By counting the periods, I can also regulate the power of an AC water filter and aeration.

You can write 4 programs (located in programs.ino) and then select which is going to be run on a given day. These program call every minute to check if something is supposed to happen.

I'm using a 12V heating element that can be regulated by turning on or off between a 1°C threshold or by using PWM (either with linear or quadratic fall-of) to gradually heat up less and less before the set temperature.

To power the heating I am using an AC to DC 12V 50W power supply. I have a small step-down DC to DC converter to power the Arduino.

There is a red LED that indicates errors. (for example if the thermistor disconnects the LED will start blinking)

Variations

• Main cover - The cut version represents how I divided the part so I could print it. The whole version is there if you want to cut it differently.
• Electronics cover: There is a version with inside holes for magnets so you can attach a led holder easily.
• Electronics cover - Part 4: Here you can put some holes for wires, tubes etc. so you can access the insides without needing to remove them.

Print guide

Printed on the K1 Max :

• Nozzle size: 0.4mm
• Layer height: 0.16mm
• Material: PET-G
• Supports: Added along long overhangs and opened edges.

For printing I cut the main cover into 4 smaller pieces that. Then I printed them upside down to reduce supports required. Afterwards I “welded” the parts together with a soldering iron.

To put magnets in I put a pause command when slicing so I could place them and have them sealed off when printing. Be sure to secure those magnets when printing so they won't attach to the extruder.

Parts used:

1. Arduino nano
2. 12V 50W power supply
3. 12V to 5V step-down converter
4. 6x Screw 2x10mm 
5. 12x Screw 2x5mm (I just cut short the 2x10mm)
6. 12x 10x5mm magnets (for LED holder)
7. LED strips
8. Aeration, filtration and heaters
9. Custom PCBs to connect everything together

Software used:

• Arduino IDE
• KiCad 7.0
• Onshape

Libraries used:

• ArduinoMenu - Manages the menu system
• ClickEncoder - Used to handle the rotatory encoder
• LiquidCrystal - Used to control the LCD display

Code and Wiring diagram are included in a zip file. (Most of the comments are written in Czech)