For many the effort of this solution will probably appear as over engineered, however I found the electronic and programming both challenging and interesting (I'm new to electronics, less so to programming).
A micro-controller does the following
* Opens a solenoid valve which causes a treatment barrel to fill up with water. A switch indicates to the controller when the max level is reached
* Treats the water with water conditioner through a Peristaltic dosing pump
* Heats the water (I actually don't have the heaters and may decide not to bother)
* Partial drains the aquarium, a float switch indicates when the drain is complete.
* Fills the aquarium, a float switch indicates when the max level is reached.
This happens every sunday at 9am :-)
Below is a pictorial overview, everything you see here is 12V. This is not a build guide, this post doesn't cover the software aspect (which I made from scratch).
The general process is as follows.
1. Like all good things, water comes from the tap. Of interest would be the black poly pipe which is burried in the garden and is out of side
![](http://img571.imageshack.us/img571/3012/img20120729100806.jpg)
2. A solenoid box I picked up at Bunnings.
![](http://img692.imageshack.us/img692/9756/img20120729100943.jpg)
3. Inside the solenoid box: A 12v solenoid that electrically allows water from the tap to be opened and closed.
(the exposed wires you see are a flyback diode and I'll explain this in another post)
![](http://img207.imageshack.us/img207/6986/img20120729100906.jpg)
4. This is a 210L Rain water tank you can get from Bunnings for a 100 bucks. When the solenoid is opened this container is filled.
Unfortunately I didn't grab pics of the inside, but it's worth knowing there is
1. Float switch to indicate when the tank is full
2. A dosing pump to add conditioner
3. Provision for a barrel heater (probably the only 240 component if implemented)
4. 12v pump to pump out into the aquarium - see image 6, it is the same pump.
![](http://img526.imageshack.us/img526/9828/img20120729101001.jpg)
4.1 Here's a top view of the barrel (get a decent drill, its a very think plastic lid)
![](http://img842.imageshack.us/img842/940/img20120729101023.jpg)
5. Now we move into the house. Perth homes often have double brick making any hole a mission.
I suggest you find a tradesman with a core drill (and about $100 in change). The result will be the cleanest cylindrical hole.
There is a risk the plaster will crack on the drills exit. For this reason it was drilled from the outside in and any lost plaster on the inside can be patched up (or hidden by a flange which I don't yet have)
Make sure you line the inside of the hole, otherwise you'll fail your terminate inspection.
This has two pipes (water in, water out) and some cabling for the solenoid, pumps and float switches
![](http://img600.imageshack.us/img600/3372/img20120729101217.jpg)
6. This pump (ebay) is a 12V 1amp pump. Right now I just dunk it into the tank. Going forward the pump will be inside the cabinet (below the water line) - less things in the tank, and the pump don't go biological on me.
You don't really need a powerful pump here, there's zero head height as the pipes terminus is below the water line.
![](http://img838.imageshack.us/img838/6184/img20120729101409.jpg)
7. Now to the automation. I've used custom, open source micro-controller. It looks neater when the cables are tied up and the box is closed. The red circuit board is the real time clock so I can schedule my water change.
The code I wrote from scratch, much to improve but it does the job. Happy to share if anyone wishes to replicate :-)
![](http://img221.imageshack.us/img221/8707/img20120729101258.jpg)
8, One of problems with pumping out water from the aquarium is that once the pump stops water continues to flow due to the perfect siphon that is created. A micro-solenoid valve wired in parallel to the pump fixes that. When there's no power the valve is closed and no accidents occur,
![](http://img401.imageshack.us/img401/5170/img20120729101319.jpg)
9. I'll get a full shot of my tank later, till then here's a video of it