Hanna Chlorine Checker to test Saltwater

Zalick · 11/14/2016, 11:09 PM

I tested my saltwater using my hanna total chlorine checker and it showed .62 total chlorine. I freaked out and dumped all 40g of saltwater. I tested my 40g of fresh and it tested 0. I rinsed and cleaned my saltwater container and transferred the fresh to it and made up a new batch of saltwater. I tested the saltware again 24hrs after mixing and it tested .39 on the checker.

Is there something in saltwater that reacts with the reagent to appear like chlorine? The test tubes have the cloudy flakes just like if there were chlorine in the water.

I'm assuming my kents reef salt does not have chlorine in it, and I know the freshwater had no chlorine, so.....any ideas why it would test positive?

Zalick · 11/15/2016, 12:39 PM

In case anyone else has the same issue, I received this reply from Hanna. Great customer service FYI.

INTERFERENCES
Bromine (positive error)
Oxidized Manganese and Chromium (positive error)
Chlorine dioxide (positive error)
Ozone (positive error)
Iodine (positive error)

In case of water alkalinity greater than 250 mg/L CaCO3 or acidity greater than 150 mg/L CaCO3
the color of the sample may develop only partially, or may rapidly fade. To resolve this,
neutralize the sample with diluted HCl or NaOH.

In case of water with hardness greater than 500 mg/L CaCO3, shake the sample for approximately
2 minutes after adding the powder reagent.

bertoni · 11/15/2016, 04:56 PM

So did they state that saltwater would interfere? I'm not sure about the chemistry of this kit. Saltwater certainly has some bromide and iodide in it.

Zalick · 11/15/2016, 05:04 PM

Quote:

Originally Posted by bertoni

So did they state that saltwater would interfere? I'm not sure about the chemistry of this kit. Saltwater certainly has some bromide and iodide in it.

I specifically asked if the Total Chlorine Colormeter could be used with saltwater since there was no limitation listed in any of the manuals. He did not answer that question specifically but told me the above things that could interfere.

I thought this would be good information to know for reefers. I neglected to test my RO water for a bit and then saw some chlorine breakthrough. I test my tank water and it showed .08 ppm which made me a bit nervous. Based upon the answer from Hanna, the chlorine checker should not be used for testing reef tank saltwater, only RO.

bertoni · 11/15/2016, 05:28 PM

Oh, sigh, well, that's good to know.

Dan_P · 11/15/2016, 08:16 PM

It would seem that anything that can oxidize iodide will give a positive test (see test information below).

If freshly prepared saltwater doesn't give a positive test, then there is something in the aquarium water oxidizing the iodide would be my conclusion. If not inorganic, is there an organic or enzymatic substance or even a microorganism behind this?

EPA-NERL: 330.5: Total Residual Chlorine by Spectrophotometer

https://www.nemi.gov/methods/method_summary/5237/

Chlorine (hypochlorite ion, hypochlorous acid) and chloramines stoichiometrically liberate iodine from potassium iodide at pH 4 or less. The liberated iodine reacts with N,N-diethyl-p-phenylene diamine (DPD) to produce a red colored solution. The solution is spectrophotometrically compared to a series of standards, using a graph or a regression analysis calculation.

Any oxidizing agents; these are usually present at insignificant concentrations compared to the residual chlorine concentrations. Turbidity and color will essentially prevent the colorimetric analysis.

11/14/2016, 11:09 PM	#1
Zalick My reef tanks my wallet Join Date: Dec 2011 Location: Portland Posts: 571	Hanna Chlorine Checker to test Saltwater I tested my saltwater using my hanna total chlorine checker and it showed .62 total chlorine. I freaked out and dumped all 40g of saltwater. I tested my 40g of fresh and it tested 0. I rinsed and cleaned my saltwater container and transferred the fresh to it and made up a new batch of saltwater. I tested the saltware again 24hrs after mixing and it tested .39 on the checker. Is there something in saltwater that reacts with the reagent to appear like chlorine? The test tubes have the cloudy flakes just like if there were chlorine in the water. I'm assuming my kents reef salt does not have chlorine in it, and I know the freshwater had no chlorine, so.....any ideas why it would test positive?

11/15/2016, 04:56 PM	#3
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	So did they state that saltwater would interfere? I'm not sure about the chemistry of this kit. Saltwater certainly has some bromide and iodide in it. __________________ Jonathan Bertoni

11/15/2016, 05:28 PM	#5
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	Oh, sigh, well, that's good to know. __________________ Jonathan Bertoni

11/15/2016, 12:39 PM	#2
Zalick My reef tanks my wallet Join Date: Dec 2011 Location: Portland Posts: 571	In case anyone else has the same issue, I received this reply from Hanna. Great customer service FYI. INTERFERENCES Bromine (positive error) Oxidized Manganese and Chromium (positive error) Chlorine dioxide (positive error) Ozone (positive error) Iodine (positive error) In case of water alkalinity greater than 250 mg/L CaCO3 or acidity greater than 150 mg/L CaCO3 the color of the sample may develop only partially, or may rapidly fade. To resolve this, neutralize the sample with diluted HCl or NaOH. In case of water with hardness greater than 500 mg/L CaCO3, shake the sample for approximately 2 minutes after adding the powder reagent.

11/15/2016, 08:16 PM	#6
Dan_P Registered Member Join Date: Aug 2014 Posts: 1,432	It would seem that anything that can oxidize iodide will give a positive test (see test information below). If freshly prepared saltwater doesn't give a positive test, then there is something in the aquarium water oxidizing the iodide would be my conclusion. If not inorganic, is there an organic or enzymatic substance or even a microorganism behind this? EPA-NERL: 330.5: Total Residual Chlorine by Spectrophotometer https://www.nemi.gov/methods/method_summary/5237/ Chlorine (hypochlorite ion, hypochlorous acid) and chloramines stoichiometrically liberate iodine from potassium iodide at pH 4 or less. The liberated iodine reacts with N,N-diethyl-p-phenylene diamine (DPD) to produce a red colored solution. The solution is spectrophotometrically compared to a series of standards, using a graph or a regression analysis calculation. Any oxidizing agents; these are usually present at insignificant concentrations compared to the residual chlorine concentrations. Turbidity and color will essentially prevent the colorimetric analysis.