Boomer
Well-known member
Here's my conclusion:
Conclusions
My conclusion based on limited testing of two Pinpoint Calcium monitors, and from the information that I have received from several other aquarists who have them, is that they can be a useful way to measure calcium, but are not without issues that aquarists must become familiar with. Given the time to calibrate and equilibrate them to each new solution, such a monitor is not faster than a test kit. Since I have not tested the accuracy of any calcium test kits, I cannot compare the accuracy of the calcium monitor to typical commercial kits.
I was pleasantly surprised by the fact that the response does not seem likely to be thrown off by the ranges of different water chemistries encountered in reef aquaria. Temperature seems to be the only big concern, and that is something that aquarists can control.
The monitor is warranteed for 2 years, and it is recommended to replace the electrode after 18-24 months, or when it can no longer be calibrated. Pinpoint has replaced monitors for some folks that had problems (unable to calibrate). All of the measurements that I took were using the 9 volt battery, although one of the meters did come with an AC adapter.
The section below gives some tips for using the Pinpoint calcium selective electrode in reef aquaria. Pinpoint includes many other recommendations in their User’s Guide, which is well written and easy to follow. I have only listed those things here which are not listed there, or which I consider most important:
1. The calcium monitor will probably not give reliable readings for any solution other than seawater. I would not use it for fresh water, limewater (kalkwasser), or calcium supplement solutions (at least not using the Pinpoint seawater standards). It may or may not work properly in the low pH/high alkalinity solutions found in the effluent of a calcium carbonate/carbon dioxide reactor.
2. Temperature is critically important. Make sure that the calibration temperature and the measurement temperature are the same to within 1-2 ºF.
3. The electrode takes a while to equilibrate to the new solution. The longer it is left in, the more reliable will be the reading (within reason, very long times of a day or more may start to encounter some drift). The directions say to equilibrate during calibration until the meter gives 4-5 flashes of the concentration without stopping, but I would suggest leaving it in until it flashes steady without stopping. In taking measurements, I would leave it in for at least 10 minutes and watch the reading to see that it is not changing.
4. Do not tough the tip directly. It can be easily damaged.
5. The directions say to rinse the probe in fresh water between measurements or calibrations. If you are measuring a large volume, like a reef system, that isn’t important. If you are measuring in a small container (like a cup), it is more important to not transfer water between samples. Bear in mind, however, that some fresh water clinging to the probe will alter a measurement more than will the 100 ppm standard if you are going to read seawater. My suggestion is to gently shake the electrode between solutions to remove big drops, and possibly wipe the sides gently with a paper towel if you are taking careful measurements.
6. Turn off the meter between uses. It remembers the previous calibration, so there is no need to run down the battery.
Disclosure: American Marine/Pinpoint supplied the two calcium meters that I tested at no cost.
__________________
Randy Holmes-Farley
Want to talk chemistry? Try the Reef Chemistry Forum at Reef Central
This article is not out yet but will be soon Boomer
Conclusions
My conclusion based on limited testing of two Pinpoint Calcium monitors, and from the information that I have received from several other aquarists who have them, is that they can be a useful way to measure calcium, but are not without issues that aquarists must become familiar with. Given the time to calibrate and equilibrate them to each new solution, such a monitor is not faster than a test kit. Since I have not tested the accuracy of any calcium test kits, I cannot compare the accuracy of the calcium monitor to typical commercial kits.
I was pleasantly surprised by the fact that the response does not seem likely to be thrown off by the ranges of different water chemistries encountered in reef aquaria. Temperature seems to be the only big concern, and that is something that aquarists can control.
The monitor is warranteed for 2 years, and it is recommended to replace the electrode after 18-24 months, or when it can no longer be calibrated. Pinpoint has replaced monitors for some folks that had problems (unable to calibrate). All of the measurements that I took were using the 9 volt battery, although one of the meters did come with an AC adapter.
The section below gives some tips for using the Pinpoint calcium selective electrode in reef aquaria. Pinpoint includes many other recommendations in their User’s Guide, which is well written and easy to follow. I have only listed those things here which are not listed there, or which I consider most important:
1. The calcium monitor will probably not give reliable readings for any solution other than seawater. I would not use it for fresh water, limewater (kalkwasser), or calcium supplement solutions (at least not using the Pinpoint seawater standards). It may or may not work properly in the low pH/high alkalinity solutions found in the effluent of a calcium carbonate/carbon dioxide reactor.
2. Temperature is critically important. Make sure that the calibration temperature and the measurement temperature are the same to within 1-2 ºF.
3. The electrode takes a while to equilibrate to the new solution. The longer it is left in, the more reliable will be the reading (within reason, very long times of a day or more may start to encounter some drift). The directions say to equilibrate during calibration until the meter gives 4-5 flashes of the concentration without stopping, but I would suggest leaving it in until it flashes steady without stopping. In taking measurements, I would leave it in for at least 10 minutes and watch the reading to see that it is not changing.
4. Do not tough the tip directly. It can be easily damaged.
5. The directions say to rinse the probe in fresh water between measurements or calibrations. If you are measuring a large volume, like a reef system, that isn’t important. If you are measuring in a small container (like a cup), it is more important to not transfer water between samples. Bear in mind, however, that some fresh water clinging to the probe will alter a measurement more than will the 100 ppm standard if you are going to read seawater. My suggestion is to gently shake the electrode between solutions to remove big drops, and possibly wipe the sides gently with a paper towel if you are taking careful measurements.
6. Turn off the meter between uses. It remembers the previous calibration, so there is no need to run down the battery.
Disclosure: American Marine/Pinpoint supplied the two calcium meters that I tested at no cost.
__________________
Randy Holmes-Farley
Want to talk chemistry? Try the Reef Chemistry Forum at Reef Central
This article is not out yet but will be soon Boomer
