Salinity/Conductivity Meter Ideas?
- Thread starter bkiba
- Start date
bkiba
Premium Member
I was doing a lot of searching last night on inductive conductivity sensors, which could be used for salinity measurment. However it seems the available hardware is north of $500 just for the sensor. I don't know how confident I am that I can overcome the technical issues in designing such a sensor.
Are the current direct contact sensors suitable for constant exposure to saltwater? I seem to remember online constant monitoring on a few fish tanks I have visited over the years. What is the calibration schedule and what are the probes made from so they do not corrode (titanium? gold?)?
thanks again
Ben
Are the current direct contact sensors suitable for constant exposure to saltwater? I seem to remember online constant monitoring on a few fish tanks I have visited over the years. What is the calibration schedule and what are the probes made from so they do not corrode (titanium? gold?)?
thanks again
Ben
bkiba
Premium Member
Inductive sensors are really cool because they induce a voltage in the medium (a lot like RFID tags) and then are able to measure the current induced by measuring the magnetic field around the medium. They seem new and fancy but I really like the idea. They are totally electrically non-contact - so perfect it seems for a reef.
I don't want to deal with corroded electrodes. That is why I was thinking of using gold or titanium. I'm going to try titanium, gold is a little too pricey for me at the moment
. It looks like a lot of commecrial probes use graphite electrodes - I assume they must be quite stable, electrically, so I am going to try out both titanium and graphite. I'll report back when I have done some testing on corrosion and effectivness of both. Titanium has a pretty low electical conductivty so it might require a higher voltage to get a reliable reading. It seems like graphite can be directionally conductive, so that will make for some interesting behavior I'm sure.
If anyone comes across a schemitic for an inductive sensor, how to drive/read those sensors, or anything else about them, please post it here.
thanks
Ben
I don't want to deal with corroded electrodes. That is why I was thinking of using gold or titanium. I'm going to try titanium, gold is a little too pricey for me at the moment
. It looks like a lot of commecrial probes use graphite electrodes - I assume they must be quite stable, electrically, so I am going to try out both titanium and graphite. I'll report back when I have done some testing on corrosion and effectivness of both. Titanium has a pretty low electical conductivty so it might require a higher voltage to get a reliable reading. It seems like graphite can be directionally conductive, so that will make for some interesting behavior I'm sure.If anyone comes across a schemitic for an inductive sensor, how to drive/read those sensors, or anything else about them, please post it here.
thanks
Ben
HeneryH
Henery Hawk
I don't want to be flip here but isn't salinity the most stable tank parameter there is? If you top-off with fresh water then there should be little to zero change right?
For something so stable I wonder if realtime monitoring is necessary.
I may be totally wrong though, wouldn't be the first time
For something so stable I wonder if realtime monitoring is necessary.
I may be totally wrong though, wouldn't be the first time
uncleof6
Active member
To add a little more perspective, Salinity is one of the top ten things that should be monitored and/or controlled in a reef aquarium. Some list only eight, but I insist on ten
Calcium
Alkalinity (bicarbonate level)
Salinity
pH
O2
CO2
Magnesium
Phosphate
Ammonia
Regards,
Jim
Calcium
Alkalinity (bicarbonate level)
Salinity
pH
O2
CO2
Magnesium
Phosphate
Ammonia
Regards,
Jim
HeneryH
Henery Hawk
My point was not that it should not be monitored but that it does not change very much and is very stable. Matt points to a condition where it is not so stable so there is another perspective.
My Salinity changes very little so for me (just for me,maybe not for others) spot checking with the refractometer is much more economical and provides no less data.
For others, maybe realtime collection of salinity is needed.
My Salinity changes very little so for me (just for me,maybe not for others) spot checking with the refractometer is much more economical and provides no less data.
For others, maybe realtime collection of salinity is needed.
bkiba
Premium Member
I'm going to look at the following items in this order
Exposure of titanium to saltwater and elecrtical properties
Exposure of graphite to saltwater and electrical properties
Simple conductivity circuit (2 pole) and the behavior of the two materials of interest.
More complex (2 pole) AC conductivity circuit
4 - pole AC conductivity probe
Maybe an inductive desgin if I get brave
Maintenance of the probe is going to be the biggest deciding factor. I'm not sure how it will behave when stuff starts adhereing to it. The AC design is cool because it doesn't have a constant voltage at any one probe, so you won't get electrolosys causing deposits of Calicum or whatever at an anode/cathode. That is the theory at least. The current measurment gets a little more complex with AC but it still shouldn't be too difficult.
The 4 pole idea is another cool concept. You keep the AC excitation of the media, but there are 2 outer poles that do the excitation, in between those are 2 inner poles that are used to measure the voltage/current flow.
Exposure of titanium to saltwater and elecrtical properties
Exposure of graphite to saltwater and electrical properties
Simple conductivity circuit (2 pole) and the behavior of the two materials of interest.
More complex (2 pole) AC conductivity circuit
4 - pole AC conductivity probe
Maybe an inductive desgin if I get brave
Maintenance of the probe is going to be the biggest deciding factor. I'm not sure how it will behave when stuff starts adhereing to it. The AC design is cool because it doesn't have a constant voltage at any one probe, so you won't get electrolosys causing deposits of Calicum or whatever at an anode/cathode. That is the theory at least. The current measurment gets a little more complex with AC but it still shouldn't be too difficult.
The 4 pole idea is another cool concept. You keep the AC excitation of the media, but there are 2 outer poles that do the excitation, in between those are 2 inner poles that are used to measure the voltage/current flow.
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HighlandReef
Chalice Monger
taggin on
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