Does anyone know where to get electronic sensors for use in aquariums (like probes or components) or circuit projects that can be built to do so? I'd like to make a digital data-logger for my aquarium which could send the info to my computer.

I've been planning something like this, but with active feedback control. I've assummed I'll have to do it all from scratch.

Temperature can be measured with a home made thermocouple, which will probably be the best bet. If that was fed back to a heater, you could control the temperature while making sure the rate of temperature change was always slow enough not to shock the fish.

You could also measure light levels with a simple photodiode and link it to the lights in the tank so the total light level varied regularly over 24 hours so they could have a simulated day even indoors.

pH sensors can be bought frmo temperature suppliers, but I'm still looking for a better source. These also need regular calibration. This could be automated, and that's my plan, but it would be a big job to do.

I know you can also get electronic oxygen sensors, but those are again pricey.

Ultimately I'd like to have a full electronic control system built into a large hood for the tank that can be programmed with the data of what fish are present, what plants, other animals, tap water parameters, etc, and can control the water quality in most respects, or give advice on screen if outside intervention is needed.

But that will all take a very long while. If I even do it at all...

Wow that sounds quite ambitious! The only active feedback that I was envisioning for my system would be email and alarm notifications if something went wrong and cutting power to the pump if the water level decreases. I'd also like graphs of all my water params.

I'll let you know if I find any useful information that can help you with your project!

gosh, this is totally out of my world...

sounds like building a racing car to me..

sorry, if only I can help but I am very interested to know what equipment you guys may have that is not for sale in shops that can be shared for us to learn?

wow, sounds like you guys have quite a job. albert, you may try radio shack for your sensors and stuff, i ahve found alot of my stuff there. I am not sure what part of the us are you are from, but i atleast know radio shacks are all over the east coast. I say there should be a post where braniacs can come together with ideas and things to try with this experiment.

Albert,

You will need a software package called Labview or a similar one. This program logs data received from a series of instruments and may control electrical equipment. You will also need an interface between the measuring device and the software, National Instruments has its FieldPoint modules to do that. For pH, temperature, and oxygen probes try Fischersci.com or Colepalmer.com
I have a labscale reactor at my university that does biological treatment of water and those places are where we got most of the equipment.

What you are trying to do sounds like a great idea. Oxygen and pH probes are around $200 each, the pH/O2 meter may be over $800, FieldPoint modules are around $500...

Hope this helps

Ooh, a little too rich for my blood. I was hoping to build the device and software as a free-time project, but I have been unable to find inexpensive test sensors except for pH (and some sensors just don't exist at all).

I am sure you will find temperature, oxygen, CO2, and pH probes... look for used lab equipment in the web, you might get lucky find unexpensive instruments that are no longer fit for labs but may work great for you