Fish tank monitoring system

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Fish tank monitoring system

Postby SparkyST » Tue Jun 11, 2013 12:53 pm

HI guys

I got a Raspberry Pi for my bday today and was thinking if I could turn it into a monitoring system for my tank. e.g. Water temp, ammonia, nitrite and nitrate.

Does anyone know if there are any sensors that can measure this in the water so I can program the Pi to report back on levels etc in the tank?
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Re: Fish tank monitoring system

Postby theomen » Tue Sep 03, 2013 12:31 am

Hello Sparky

It is possible yes. I#m guessing since your toying with pi you have a basic knowledge of electronics?

Personally i would start with water temp as its probably the easiest. Google will be you friend for lots of basic circuit diagrams. No i have never worked with a PI so am not sure of its capability's however i suspect a basic circuit would consist of a temperature probe followed by a voltage follower ( just a simple unity gain op amp will stop the voltage being affected by any load current that may occur). The next stage is to measure the voltage produced and feed it to your pi. Personally i would then go with a voltage to frequency converter. Is the pi capable of measuring frequency? if not then you will then need a frequency counter (again a simple IC is available for this). this should then be able to be fed in to you PI and used to measure temperature. Although the above are all readily available IC there is still a small amount of work in regards to R and C values but again all pretty simple stuff.

Next i would look at a PH sensor. Again a similar principle to the above as you can get PH sensors which vary in voltage dependent on ph level . The probes i have used in the past PH7 is normally 0v, +ve voltage is higher PH, -ve voltage would be lower ph. although the change is only mV at most. Be warned though these are not cheap.


As far as im aware there are three methods used to do this digitally.

1. Using a colourmetric analyzer,basically a posh term for digitally measuring the intensity of a specific wavelength of light.Using reagents a sample of water would change colour much like normal test we carry out but then measured digitally as opposed to using the human eye.

2. Using UV absorbance spectrophotometers. There method of measuring how much UV light is absorbed by a sample of water. A measured amount of Uv light is passed through the sample and remeasured once passed through the sample. It is only possible by added different reagents to the sample ( i wont go in to the chemistry) but the reagents change the sample chemically enabling it to absorb specific amounts of uv light.

3.Using Ion-selective electrodes. Again reagents are added to the sample water altering the ph levels and thus creating free ammonia in the solution. The electrode then measures the change in PH level caused by free ammonia. This is then compared to a reference electrode. Calibration is done such that a Ph rise of X equates to an ammonia level of Y.

In short all three of these methods are very accurate but because of the need for external reagents are not suited to constant measuring systems.

I'm not familiar with nitrate measurements but i know you can get digital spot checkers but these require calibaration before each use so like the ammonia measurements are not suited to constant monitoring.

If i can be of anymore help let me know.

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Re: Fish tank monitoring system

Postby SparkyST » Tue Sep 03, 2013 8:15 am

Thanks Damien

Thats some good info there and will get me googleing away :) Just need to find the time to sit down and look at it all and get it working. :D
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Re: Fish tank monitoring system

Postby brodie » Mon Oct 07, 2013 8:41 am

Hi alll ... !
Yeah i am using Pi in my tank . But befotre using this you should must have knowledge about electronics . And for senso you should concern with marine services they will guide you in better way .

Please make a suggestion.

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