Tropic Marin Potassium Test Professional

Measuring range: 300 - 500 mg/l
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Resolution: 5 mg/l

Potassium is a vital macronutrient for all living things. In natural seawater, the alkali metal is present in an average concentration of 408 mg/l. In saltwater aquariums, the potassium concentration can usually be kept stable by changing the water regularly. However, a potassium deficiency can occur in individual tanks due to the use of zeolites and other adsorbers. A sign of a possible potassium deficiency is the significant discoloration of the corals and the retraction of the polyps. In saltwater aquariums, the potassium concentration should be checked regularly and kept between 380 and 420 mg/l.

12 ml potassium standard (400 mg/l)
25mL Reagent A
25mL Reagent B
5 ml reagent C
30 ml reagent D
2 glass cuvettes 10 ml
3 dosing syringes 1 ml with attachment
1 instruction manual

Note on the potassium test: The accuracy of the measurement results can be increased by determining a correction value. For this purpose, a measurement is carried out using the potassium standard. This measurement results in a correction value that should be taken into account for every potassium measurement. We recommend re-determining the correction value every 3-4 weeks.
 
Instructions:
 
Attention: In order to avoid mutual contamination, the dosing syringes with the syringe attachments may only ever be used for the same reagents! In addition, the glass cuvettes, syringes and syringe attachments used MUST be cleaned immediately after each series of measurements!
Immerse the syringe in the liquid when drawing up. The metering syringes are always read from the piston, even if there is air between the piston and the liquid (due to the dead volume of the syringe attachment). The air bubble does not affect the test result.
 
1. Determination of the correction value:
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 If you have only recently determined the correction value, go to point 2 “Determination of potassium”.
 Shake all reagent bottles before use!
 Place a clean attachment on the 1 ml dosing syringe with a green plunger that is as dry as possible and draw up 1 ml of potassium standard. Pour the entire amount into one of the two cuvettes.
 Now carry out the potassium measurement as described under points 2.3 to 2.8.
 The correction value can now be determined using the table below. To do this, take the corresponding potassium concentration of the remaining amount of reagent D from the table. Subtract this value (measured potassium concentration) from the standard value of 400 mg/l (concentration of the potassium standard). This will give you the correction value that you can apply to the measured values ​​determined later.
 For example:
 Remaining amount of reagent D1: 0,48 ml
 Potassium concentration K1: 420 mg/l
 Calculation: 400 mg/l – 420 mg/l = – 20 mg/l.
 Result: Subtract a correction value of 20 mg/l from future potassium measurements. If you determine a positive value, add this to future potassium measurements.
 Thoroughly clean the glass cuvette, syringes and syringe attachments used at the latest after carrying out the actual potassium measurements.
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2. Potassium determination:
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 Shake all reagent bottles before use!
 Place a clean attachment on the 1 ml dosing syringe with a green piston, rinse the syringe several times with the water sample to be examined (aquarium water) and then draw up 1 ml of this water. Pour the entire amount into the clean second cuvette.
 Place a clean attachment on the 1 ml dosing syringe with red printing and draw reagent A up to mark 20 on the syringe (corresponds to 0,5 ml). Add the entire amount to the water sample. The exact execution of this step is crucial for the accuracy of the end result!
 Swirl the cuvette with the water sample for 10 seconds to mix the reagent well and then wait 5 minutes. A white cloudiness forms.
 Add 9 drops of reagent B, swirl for 10 seconds and let the cuvette stand for another 2 minutes.
 Then add 3 drops of reagent C from the dropper bottle; the water sample turns yellow.
 Now place another clean syringe attachment on the third 1 ml dosing syringe with black printing and draw up 1 ml of reagent D. Add three drops of reagent D to the water sample (note: under no circumstances should a large amount of reagent D be added to the cuvette at once!) and mix the reagent thoroughly by swirling carefully. This is important in order to get a clear transition point later. Repeat this process until the yellow color disappears and turns into a pale pink.
 Now carefully continue the titration. After each individual drop of reagent D, the cuvette must be swirled until a strong pink color appears after approx. 1-3 drops. Read the remaining amount of reagent D in the syringe.
 Note: If you are unsure whether the end point of the titration has been reached, add another drop of reagent D. If the color intensification does NOT increase further, the end point of the titration has already been reached. Then add the last drop (0,01 ml) back to the remaining amount. If you determine the correction value using the standard at this point, continue with point 1.5. For the actual potassium measurement of your water sample, please continue the measurement with point 2.9.
 The corresponding potassium concentration can now be read in the table below using the remaining amount of reagent D. From this value - if previously determined - the correction value determined under point 1.5 is deducted (negative value) or added (positive value).
 For example:
 Remaining amount of reagent D2: 0,40 ml
 Potassium concentration K2: 400 mg/l
 Determined correction value: – 20 mg/l
 Calculation: 400 mg/l – 20 mg/l = 380 mg/l
 Result: The potassium concentration of the tested water sample, taking the correction value into account, is 380 mg/l.
 If further measurements are carried out immediately, the cuvette(s) and the syringe with the green piston should be briefly cleaned with reverse osmosis water. After completing the series of measurements, the glass cuvettes in particular should be thoroughly cleaned immediately according to point 3 so that the precipitates do not become too stuck.
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3. Cleaning the glass cuvettes and syringes:
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After completing a series of measurements, we recommend cleaning the glass cuvettes, syringes and syringe attachments used.
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 Rinse the syringes and associated syringe attachments thoroughly with reverse osmosis water and allow to dry.
 Rinse the glass cuvette thoroughly with tap water. Clean the cuvette as best you can with a piece of kitchen paper, rinse it with reverse osmosis water and let it dry. A light precipitation may remain. To remove this, we recommend using a suitable brush such as the Tropic Marin® cuvette brush (sold separately) or adding household vinegar or vinegar cleaner. Allow the vinegar solution to take effect for 12 – 24 hours and then rinse the cuvette with reverse osmosis water and leave it dry.
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Shelf life 6 months after opening. Store in a dark and cool place.