ca monitor

[galleon]

The calibration fluids are basically 32-33 ppt salt level with a Magnesium background 1200-1400 ppm + the appropriate Calcium level.

This does sound like it would resolve much of the junction potential and ionic strength issues that would arise from calibration of the slope for measuring the ion in seawater.

Randy, from my understanding, Mg2+ is not an interfering ion for the PVC membrane, and any alkaline error comes from Zn2+ and Pb2+.

[galleon]

FWIW, I also ordered a unit from Champion today.

[SEAREEF]

id pay 500 if it works
249 is a steal ............................................

[joelsaxton]

I have been testing it out - my first unit was defective so they replaced it for me.

[mattseattle]

defective how?

[joelsaxton]

Originally posted by mattseattle
defective how?

don't know for sure - but I am fairly sure it was the probe tip. It is a PVC membrane and I think it was just a bad one. They replaced the whole set-up though.

[SEAREEF]

I just got one of these in my hands ,ill have it hooked up soon

[Fastmarc]

Originally posted by loudell
My suggestion to set up a 3 cup monitoring station is is an easy method that verifies your calibration immediately before and keeps the probe very clean by ultimately returning it to a clean calibration fluid or the probe storage bottle. You can monitor the calcium in your system and take 100 samples an hour if you want using the 3 cup method. This gives you a good sample read and keeps the probe clean, also at a proper fluid level and algae free.

Lou, thanks for chiming in also.
I am still confused by the 3 cups method though. How would you prevent the calibration fluid from being contaminated or evaporation if the tops are open and you are using it to store the probe in which would make it difficult to seal it (Seran wrap?)or are you suggesting to use new fluid each time?
Maybe I'm just having a 'dense' moment.

[loudell]

Hi Marc, The Calcium Calibration fluid is not like pH calibration fluids and is not subject to oxidation when exposed to the air. Contamination is limited to clinging drops of fluid on the probe which are put into a different value fluid. In my experience most reef hobbists are more fastidious than most pharmacists. I didn't think of covering a portion of the cup top with plastic wrap; nice idea. I'm going to try it. I've used the 3 shot glasses and I draw a black line on the outside of the glass with a sharpie marker. If the level drops because of evaporation I would replace the fluid with deionized. The calcium, magnesium or salinity won't evaporate.
Hope this was helpful..

[loudell]

Hi Marc, The Calcium Calibration fluid is not like pH calibration fluids and is not subject to oxidation when exposed to the air. Contamination is limited to clinging drops of fluid on the probe which are put into a different value fluid. In my experience most reef hobbists are more fastidious than most pharmacists. I didn't think of covering a portion of the cup top with plastic wrap; nice idea. I'm going to try it. I've used the 3 shot glasses and I draw a black line on the outside of the glass with a sharpie marker. If the level drops because of evaporation I would replace the fluid with deionized water. The calcium, magnesium or salinity won't evaporate.
Hope this was helpful..

[cbicop]

Any results from your testing Randy?

[SEAREEF]

thx lou for coming into this thread im about to test your product ,i would like it to monitor rather than test ocasionally ,i have a 100 gal sump so i will follow your instructions

[Habib]

Lou,

May I ask a few questions if you don't mind, since the following are very likely things you have already have the results for.

By how much does the calcium reading change when:

1] the magnesium changes by 100 ppm

2] the Na+ changes by 1 0/00 (absolute value)

3] is the reading influenced by organics being adsorbed on the membrane?

4] how much is the drift per day?

5] are the results influenced by alkalinity and pH since that will have an effect on ion-pairing of borate, bicarbonate and carbonate with calcium?

TIA

[SEAREEF]

ok here is my 1st round of the info ive found after 1 hr of monitoring..
first and foremost I read the instructions 3 times ,my older brother always told me to read the instructions first ,I would ask why,he would tell me the guy who invented this knows a little more than about than i think i do . OK with that being said
everything worked perfect ,I tested with a salifert test kit ,I put my water sample in a clean glass cup and i got 430 ,then i put the probe in the glass i got 438 not too bad ,then i put it in a spot where it was easy for me to get to and little water flow ,I got 457 its been there steady for 2 hrs steady

[SEAREEF]

these seem to work great and conserve

[loudell]

Originally posted by Habib
Lou,

May I ask a few questions if you don't mind, since the following are very likely things you have already have the results for.

By how much does the calcium reading change when:

1] the magnesium changes by 100 ppm

The magnesium background in the calibration fluid is about 1300 and if the magnesium was to vary 100ppm in either direction the reading may move down 1-2% if the Mg was increased and a similar amount in an upward direction if the Mg was decreased. I've always said that this meter is really not for the beginning aquarist and if the system was an ionic nightmare results may be off.

2] the Na+ changes by 1 0/00 (absolute value)
The ionisphore imbedded in the PVC membrane is pretty resistant to a fairy wide range of Sodium. Much like pH probes potentially have sodium error at pH of 12 or better. Sodium is really not a significant error factor for the Calcium probe,

3] is the reading influenced by organics being adsorbed on the membrane?

Depends on the quality and density of the organics. Calcium, pH and ORP probes will probably change in value and also be impervelious to real changes in value if they become encrusted.

4] how much is the drift per day?

I keep the probe stored in 100ppm fluid and I may see the reading elevate from 100 to 107 in the course of a week or two.

5] are the results influenced by alkalinity and pH since that will have an effect on ion-pairing of borate, bicarbonate and carbonate with calcium?

Not significant

TIA

[Fastmarc]

Lou, thanks for the reply. It does help.
I guess to help avoid contaminating the calibration (storage) fluids, a rince in DI water would do the trick.
An instrument like this would be a great help to me as I am colour blind and it is impossible for me to test calcium on my own.
I have great confidence in my other Pinpoint equipment, so I will be giving it a try.

[SEAREEF]

After 12hrs of being in a very still spot in my sump ,my levels changed from 457-389 my actual calcium level by salifert is 430

any suggestions lou ................................................

[gbr]

seareef, that is how mine started out. I actually placed it in the sump, albeit a little deep I guess and it read dead on for about 2 hours then started to drift down. From there it got dramatically worse. Lou, I have checked the site and there are no new instructions for this meter. They are the same instructions I have and there is no mention of low flow or only so deep etc.

FWIW, I really like the PinPoint meters and pay extra for them because the other 4 I have work flawlessly...but now I know to move my ORP meter to a low flow area

[joelsaxton]

Originally posted by gbr
seareef, that is how mine started out. I actually placed it in the sump, albeit a little deep I guess and it read dead on for about 2 hours then started to drift down. From there it got dramatically worse. Lou, I have checked the site and there are no new instructions for this meter. They are the same instructions I have and there is no mention of low flow or only so deep etc.

FWIW, I really like the PinPoint meters and pay extra for them because the other 4 I have work flawlessly...but now I know to move my ORP meter to a low flow area

Interesting, mine drifts upward rather quickly. It starts at about 380 and goes to over 600 in about 2 minutes.

Joel

[joelsaxton]

my Ca monitor, not my orp, that is.

[loudell]

I'm finding that 24 hour monitoring is very situationally dependant.
There could be several scenarios regarding the drift that you are experiencing. My first indication would be to seek a much lower (still) location which may be difficult in many sumps that have high turnover. Gbr you are right and I will be sure that it is put into the User's Guide; I'll take care of that. Another scenario could be a low electrolyte situation in the probe; check that.
Also do you have a calcium reactor that is depositing effluent into the sump and perhaps the Co2 may be off and on at different times.
I am trying to equate the Calcium Monitor to the pH Monitor that was introduced 14 years ago. Originally it was intended to take a precise static measurement immediately after a thorough calibration. Then hobbyist started to leave it in the tank all the time; probably because the probe tip had to remain wet. It still gave good readings although perhaps not as precise as immediately after calibration.
The Calcium Monitor has a range of 0- almost 9800ppm actually a huge range. we are really only interested in a small segment of that range say 300-500 and therefore a little bit of drift may be more than we want to tolerate. Just like the pH monitor; one solution is to recalibrate and start over. My preferred solution is to keep the probe in a 3rd cup after the calibration fluids to take a high precision reading immediately after calibration.
I've already spoken to 2 people who basically want to calibrate once, dump the probe in the sump and just read it for the next year or two. This is NOT going to be that probe. I know that they are going to be unhappy and gave then the option to return the meter. Frankly I'm not sure that any probe can totally avoid drift.
The Calcium Monitor will be a good additon to the hobby; it will have a place and I'm sure that it will get better as we go forward. There have been many people who tried to assemble a calcium monitor from scientific catalog components and their results were basically unuasable in nearly all situations after spending $1,200-1,500
I think we are on the right track.

[joelsaxton]

this time I get a reading of 436ppm. I did not recalibrate so I don't know what changed. But I think that reading at least is somewhat accurate.

[gbr]

Joel, mine is now doing that too...shooting up that is.

SEAREEF, try this and let me know what happens...Calibrate your probe, take a reading on your tank for two minutes until the reading starts to rise, rinse the probe with RO/DI and then take a reading on the 1000+ ppm Ca. Mine reads well over 2000 and shoots up rapidly.

[SEAREEF]

im still trying different things ,ill let everybody know what i find out