Hanna Nitrate N03 tester

[fishdip22]

Do they make a test kit that is a digital read out? Or really any company that is going to give a good digital read out.

[bertoni]

PinPoint makes a nitrate meter that works in saltwater, although it's quite pricey and not all that precise. I don't think there's any alternative from Hanna, but they do introduce new meters now and then. The nitrate Checker of which I'm aware works only for freshwater testing.

[fishdip22]

Originally Posted by bertoni

PinPoint makes a nitrate meter that works in saltwater, although it's quite pricey and not all that precise. I don't think there's any alternative from Hanna, but they do introduce new meters now and then. The nitrate Checker of which I'm aware works only for freshwater testing.

It must be hard to make a digital tester as BRS has to use a 4k test kit

[nereefpat]

Hach and LaMotte make colorimeters with nitrate programs. They are obviously more expensive then our hobby test kits.

Depending on where you live, there might be a lab that can test for you. I think the agriculture lab we use charges a couple bucks per nitrate test.

I know those aren't cheap or convenient answers.

[Dan_P]

I use the Hanna PO4 Checker to “read” the Red Sea nitrate test results. Detection limit is somewhere between 0.1 and 0.15 ppm NO3. To do this you need a calibration curve (which I can share) that converts the ppm PO4 reading to ppm NO3, you need a syringe filter to clarify the test solution and you will need a matched vial to act as a blank for the Checker. Most will find this just a bit too much work to obtain a number. I have spent no time trying to make this easier. Maybe some ambitious inventor will take up the challenge.

[nereefpat]

Interesting. Did you make nitrate standards with sodium nitrate?

[Tripod1404]

Originally Posted by bertoni

PinPoint makes a nitrate meter that works in saltwater, although it's quite pricey and not all that precise. I don't think there's any alternative from Hanna, but they do introduce new meters now and then. The nitrate Checker of which I'm aware works only for freshwater testing.

Yeah spectrometric analysis of the cadmium reduction method (white to pink scale) used for measuring nitrate has chloride interference if chloride amount is higher than ~100 ppm.

Natural see water has close to 20000 ppm chloride so diluting the sample to have <100ppm is not a reliable option. With 200X dilution to achieve this, nitrate amount would be way too diluted. So even small errors in measurement would be highly noticeable when multiplied with 200 to get the concentration of nitrate in the original sample. This would greatly reduce the reproducibility. This method is also sensitive to nitirite, so that is also a concern.

There is a work around for this. You can create a nitrate standart curve with known nitrate concentrations in artificial sea water. Assuming there is 0 nitrate in the artificial sea water used, standards can be created using potassium nitrate.

But this method itself has two problems. First a different standart curve would need to be created for each measurement because even small changes in salinity would have considerable influence on measurement (due to different Cl-). So standards that match the precise salinity of the tank water are needed. Even if the tank salinity is kept constant, I think using fresh standards would be necessary since measurements analysed based on a standart curve are very sensitive to standart samples and using old standart would not be a good choice.

Second, when you measure 5-10 ppm (or lower) amounts of nitrate in a solution that has interference from ~20000ppm of chloride using a very narrow beam of light, there needs to be absolutely even mixing. There can be as high as 2000 fold difference between the concentrations of Cl- and NO3-, so even small errors due to inadequate mixing would change the results. Ideal measurement should be done while the sample is continuously stirred, but I dont think that is a option for the volumes we use in the hobby.

So all this makes it changeling to make make a reliable digital reader that can give reproducible results in a reasonable time.

[Tripod1404]

Originally Posted by Dan_P

I use the Hanna PO4 Checker to “read” the Red Sea nitrate test results. Detection limit is somewhere between 0.1 and 0.15 ppm NO3. To do this you need a calibration curve (which I can share) that converts the ppm PO4 reading to ppm NO3, you need a syringe filter to clarify the test solution and you will need a matched vial to act as a blank for the Checker. Most will find this just a bit too much work to obtain a number. I have spent no time trying to make this easier. Maybe some ambitious inventor will take up the challenge.

I did a similar thing by using the spectrophotometer that we have at the lab I work. Used salifiert kit to create standards of 0.1, 1, 2, 5, 10 ppm nitrate in fresh mixed saltwater by adding potassium nitrate. Than I measured the tank sample (again developed with salifert kit) and calculated amount based on the std curve. I gave reasonably good and reproducible results. I think the measurement was done around ~520nm, but I need to find and check my notes to be sure.

But like in your case, it took a lot more effort and time than I would be willing to spent on a consistent basis. Plus I had to use close to 10 readings worth of salifert kit materiel for a single measurement.

[fishdip22]

Originally Posted by nereefpat

Hach and LaMotte make colorimeters with nitrate programs. They are obviously more expensive then our hobby test kits.

Depending on where you live, there might be a lab that can test for you. I think the agriculture lab we use charges a couple bucks per nitrate test.

I know those aren't cheap or convenient answers.

I might look in on this as I am in PHX AZ and there is a lot of farm land around.

[knx873]

It appears exact Idip 570 and the micro20 test NO3. Not sure if they are any good or not. Can’t seem to find much on these.