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How do Deal with Low or High Seawater Chlorinity |
Introduction |
Chlorinity |
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The Chlorinity of seawater is defined as the total mass of halides expressed in chlorine equivalent. Chlorinity is determined by the Mohr-Knudsen titration, which however neglects fluorides, i.e. the consumption of titrant corresponds to total mass of following anions: |
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| Anion |
Concentration in Natural Seawater |
| [g/l] |
[%] |
| Chloride (Cl-) |
19,35733800 |
99,9997374 |
| Iodide (I-) |
0,00005076 |
0,0002622 |
| Bromide (Br-) |
0,00000007 |
0,0000003 |
| Astatide (At-) |
˜ 0 |
0 |
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As flows from the table above, the results of any chlorinity test kit used in reefkeeping practice can be considered as solely chlorine-related, the other halides can be discounted. |
Density - Chlorinity - Salinity Relation |
| T |
ρ [kg/l] |
Cl- [g/l] |
S [‰] |
25 °C |
1,020 |
16,55 |
30,5 |
| 1,021 |
17,35 |
32,0 |
| 1,022 |
17,88 |
33,0 |
| 1,023 |
18,67 |
34,5 |
| 1,024 |
19,46 |
36,0 |
| 1,025 |
19,98 |
37,0 |
| 1,026 |
20,77 |
38,5 |
| 1,027 |
21,56 |
40,0 |
| 1,028 |
22,08 |
41,0 |
| 1,029 |
22,86 |
42,5 |
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High and Low Concentration of Chlorides |
There are following main reasons of incorrect chlorinity in reef tanks:
- Use of poor-quality marine salt for seawater make-up
- Use of chlorides as the calcium and magnesium additives
- Evaporation
In both cases there are the solutions how to remedy the problem - simple one for low chlorinity and little bit more complicated for high chlorinity. |
Determining of Chlorinity |
Chlorinity of seawater is in relation to density (salinity). Therefore both parameters must be determined. |
1 - Chlorinity |
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Determine the chlorinity of your seawater sample with CS TEST Chlorinity. |
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2 - Density |
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Determine the density or salinity of your seawater sample with suitable precise refractometer, salinometer or densitometer. |
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3 - Density versus Chlorinity |
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In the table above or in Operating Instructions of CS TEST Chlorinity find expected (i.e. required) chlorinity for the density (or salinity) of your sample. |
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Dealing with Low Chlorinity |
Chlorides Dosing Calculator |
Go to the Chlorides Dosing Calculator in Support menu section and enter:
- required chlorinity
matching the density of your sample
- chlorinity determined with CS TEST Chlorinity kit
- total volume of seawater in tested system
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Chlorinity must be entered in mg / l
- i.e. the results of CS TEST Chlorinity in g / l must be multiplied by 1.000. |
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Cl- Profi Plus |
Finally press the "Calculate" button to get the amount of Cl- Profi Plus in ml to be added into your tank.
Whatever is the calculated amount of Cl- Profi Plus, it shall be applied into the tank in more shots, even for more days.
Maximum recommended one-shot application is 1 liter of Cl- Profi Plus per 1.000 liters of seawater. |
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Dealing with High Chlorinity |
The only way how to remove surplus chloride anions from reek tank is the water exchange, where part of the standard marine salt is replaced with NaCl-free marine salt - CS Marine Minerals.
After determining seawater Chlorinity, go to CS Marine Minerals Dosing Calculator in Support menu section and carefully follow instructions provided. |
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