Automatic Tank Refill System (top off system).

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biscuit495

Feeder Fish
MFK Member
Jun 26, 2009
5
0
0
Tennessee
Sorry, I posted this in the wrong place the first time and thought it would be more appropriate in the DIY section.

I got tired of having to put a gallon of water in every couple of days from the loss due to evaporation so I made this system which uses the Arduino microcontroller to automatically refill the tank from a reservoir. The system senses the water level by running a small electrical current through the water every 60 seconds. If an electrical current can pass through it has enough water. If it cannot it needs water and activates the pump after checking to see if the reservoir has sufficient water in it. I used graphite rods as the electrodes. The pump that I used is a 300gph AC draining pump for hot tubs, etc. It is switched on and off by a servo that makes 2 copper plates contact and close the circuit (It would be better to have a transistor). The reservoir I used is just a five gallon bucket although it would be better to use something bigger so as not to refill as much. I now fill the bucket every couple of weeks and it keeps the tank at a constant level for that time. It has an LED that flashes to indicate insufficient water in the reservoir. I also installed a photocell for sensing light so that the pump does not run while I am sleeping, as it is somewhat loud. I am thinking of eventually adding and automatic water change system that uses another pump to pump water out of the tank every week or so. The system has been running for about 3 months and I have had no problems with it. If you want any other information on this setup, or if you have suggestions for additions to the setup you can email me at biscuit495@gmail.com or you can just respond in this thread. Please tell me what you think. I have added some pictures below.

The whole system:


The Arduino microcontroller:


The switch for the pump:


The graphite water level sensors:


The photocell (light sensor):


The reservoir with sensor and pump:
 
I would suggest is using a solid state (or reed) relay to turn the AC power on and off. Also a float switch instead of the graphite rods save on running current through your tank.
 
I have thought of replacing the electrodes that run current through the tank. I might make a pvc tube with a floating magnet in it and then put a reed switch on the back of the outside of the tank so that when the magnet drops with the water level its magnetic field would close a circuit making the arduino turn on the pump. The problem I have always had with float switches is that they get jammed and you have to clean them. The in the tank runs through only about a millisecond every minute and it is a small amount of current so it does not affect the fish. I will definitely replace the servo with a MOSFET because I do not completely trust the servo.

One thing to note if you are using electrodes in the tank: Make sure that you do not have current running through them all the time or they will corrode and cloud up the tank and could negatively affect the fish. Make sure you do this in the reservoir also so as not to corrode the water in there. The way I have mine programmed makes the electrodes only pass current for a few milliseconds every couple of days. Thanks for the feedback!
 
That is cool. One suggestion I would make is to have some sort of safety overflow, just in case.
 
I actually already had all the parts I needed but if you don't:
-Arduino usb version - $30
-300gph Pump - probably around $30 but you could use a cheaper one.
-servo - $5-10
-bucket - free who doesent have an extra bucket?
-graphite rods - free out of a 6v battery
-led - free, easy to salvage from broken devices
-photocell - $0.30 also easy to salvage.
 
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