Any method/device to Detect Aeration in Aquarium

For starter, thanks for reading this.

I'm close to finishing my final year project with arduino. It basically is a wireless system to monitor the surrounding of the aquarium and warn the user in case something bad happens (too hot or too cold bla2) and also data logging for their research (for biotech lab).

But then they need another added notification, in case the aeration in the aquarium stops. I've googled around, and i know aeration can be controlled directly by arduino, but in my case, it is not possible since the LAB use Central Aeration System, which cannot be modified just to fit in 1 project.

So, here's the question, without touching the aeration system directly, how can i detect if the aeration has stopped in the aquarium? (btw, the device will be floating freely on top of the water in the aquarium, half-submerged).
I'm thinking along the line of IR sensor, sound detector and vibration sensor. IR would be useless once the device floats too far from the aeration bubble and sound detector, well too many irregularity needs to be considered. Vibration sensor seems close to what i want but then I doubt it would work underwater.

Any suggestion, dear arduino-ers?

You could try measuring the dissolved oxygen. (I just know these sensors exist. I have no idea how you might use one with an Arduino.)

It sounds like the aeration device is powered - can you use a current detector to tell if it is running?

pantaz - ah thank you for pointing that out. It would be exactly what I'd need, if not for the price list lol (the normal oxygen sensor is still inexpensive but the dissolve one i found so far is out of my budget)... And it cost 3 times the price it shows on the net for my country so it would not exactly be a cheap option. However i'll still google around for a while.

wildbill : The aeration is centralized, so modification is not advised ( well the University wont allow it either way). And their voltage(current) to control all those aeration system, i dont think arduino can handle it.

But maybe i can bypass the aeration's pipe to 1 certain aquarium and monitor if the air is running or not?
How do i detect that then?

How noisy is the tank? Can you do anything with a microphone? You may of course need to know what else is running (filter pumps?) to be able to use this method.

the air pump center is far from the aquarium, but i think the aeration bubble in the aquarium makes a considerable sound. I havent found any waterproof sound device for arduino yet (using a normal one and encapsulate it with waterproof case is one of the way to go, but i doubt the effectiveness). Any suggestion?

How about one of these water wheel ornaments with a magnet and Hall effect sensor? If it stops turning, no bubbles!

(Not sure about waterproofing, I must say...)

water wheel.jpg

I wouldn't bother with waterproofing, just attach the microphone (or piezo) to the glass on the outside.

I wouldn't bother with waterproofing, just attach the microphone (or piezo) to the glass on the outside.

Jeez I'm thick: that would work for my water wheel too- stick the HE sensor on the outside. DOH.

Here is the picture of one of the test aquarium (it's not really aquarium but then i dont know what to call that lol).

"Glass" is not really applicable but i'm sure it still works nonetheless. Though i may have to change the device to stay fixed at one place instead of let it roam freely like a boat because i'm afraid the sound detector might get splash by the waterfall :smiley:

I'll search for any decent microphone sensor that fits with arduino and order it tonight. I'll post any thought on it after i've integrated it.

google current transducer. it is a donut that goes around a wire. it senses if there is current in the wire. used to tell if a motor is running or not running. you could make one by wrapping a wire around a tube.

not sure if this would be of any use. but a turbidity sensor would tell how transparent the water is. if it contains air bubbles. it would not be clear. it could be put on a hose without any modification. just slip in on over the hose and the water would pass through. shine a light on on side detect reflected light around the tube. the more light on the opposite sensor the more clear the water. the more light on the sensor next to the emitter, the more reflective the water is.