Author Topic: Nitrate test meter  (Read 4023 times)

0 Members and 1 Guest are viewing this topic.

Offline akisTopic starter

  • Frequent Contributor
  • **
  • Posts: 981
  • Country: gb
Nitrate test meter
« on: January 26, 2014, 02:35:42 pm »
Hi

Does anyone know the basics/basis of how to test water for nitrates - usually it is a figure given in parts per million, ppm for short.

There are a couple of handheld meters on the market but they are prohibitevely expensive for the hobbyist aquarium keeper!

If we had a schematic or some basis of operation we might be able to design something. It does not need to be 0.1% accurate, even 10-20% will do just fine.

Many thanks
 

Online kripton2035

  • Super Contributor
  • ***
  • Posts: 2572
  • Country: fr
    • kripton2035 schematics repository
Re: Nitrate test meter
« Reply #1 on: January 26, 2014, 02:58:56 pm »
the probe itself makes the price of the meter
just poking around shows a good electrode is some $250
then it's only a 0-200mV measurement
I dont think you can make a DIY probe for that.
http://www.frederiksen.eu/uploads/tx_tcshop/media/CI-6735.pdf
 

Offline akisTopic starter

  • Frequent Contributor
  • **
  • Posts: 981
  • Country: gb
Re: Nitrate test meter
« Reply #2 on: January 26, 2014, 03:10:53 pm »
OK thanks. It appears complicated and convoluted enough even with the ready made probe!

I have bought a "total disolved solids" TDS meter very cheaply on ebay which measures ppm of total dissolved solids in water and it seems to be correct. Tap water measures at about 220-250 ppm, mildly filtered water at about 200ppm, and water coming out of my RO filter unit at just 15ppm!

I do not know how the TDS meter works but I thought the Nitrate meter would be just as simple :)
 

Offline SeanB

  • Super Contributor
  • ***
  • Posts: 16272
  • Country: za
Re: Nitrate test meter
« Reply #3 on: January 26, 2014, 03:36:10 pm »
TDS meter works by using some carbon electrodes to measure the conductance of the water. Simple to do and calibrate, and no parts to wear out, the calibration is simple to do and the dimensions of the cell are easy to measure to calculate the output.

The nitrate and such kits use the water as part of a chemical cell that makes a small voltage that is proportional to concentration. You need a specific set of electrode materials, reagents that only respond to the specified chemicals that you are interested in, a temperature sensor to provide compensation and a micropore filter to allow the reagents to contact the water. All consumable materials that are both hard to make and use with the required purity at home easily.
 

Online kripton2035

  • Super Contributor
  • ***
  • Posts: 2572
  • Country: fr
    • kripton2035 schematics repository
Re: Nitrate test meter
« Reply #4 on: January 26, 2014, 03:38:50 pm »
 

Offline PeterL

  • Regular Contributor
  • *
  • Posts: 180
  • Country: nl
Re: Nitrate test meter
« Reply #5 on: January 26, 2014, 08:19:41 pm »
You could also use this device:

http://www.iorodeo.com/colorimeter

Measuring Nitrate in an aquarium is quite a complex proces with this device, but described here in detail:

http://public.iorodeo.com/docs/colorimeter/lab_3.html
 

Offline GeoffS

  • Supporter
  • ****
  • Posts: 1272
  • Country: au
Re: Nitrate test meter
« Reply #6 on: January 27, 2014, 01:50:34 am »
Cheapest place I've found  for these sort of sensors is Atlas Scientific.
I was looking at their dissolved oxygen sensor, not sure if they also have nitrate detection.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf