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  1. #1
    Join Date
    Jul 2004

    Pinpoint SG Monitor

    I just got a PH and SG Pinpoint Monitor.

    I just recently upgraded my 55G to a 90G and added the extra 40G to the new tank using my hydrometer. Both sets of water = 1.023 so I thought, well they were equal at least in the reading.

    I calibrated my SG monitor to 53 with the solution three times now. My monitor has been reading 33. So for the last few days, I've been adding salt. I am now at 37.6. This represents about 6 coffee cups of Salt. According to the chart I'm only at 1.017. A new red sea hydrometer is reading 1.19-1.20... This makes me believe the monitor is correct.

    Just double checking my monitor represents the 1st column on the chart right? It says Pinpoint Salinity mS in the first column not the second right?

    How could my hydrometer be so off? and my tank running so low on salt?

    Other tank readings:
    temp. 78 (at night) 80 (in the day with lights)
    My PH monitor is reading 8.0...
    dhk 6
    cal 420
    nitrite 0
    am 0
    nitrate 10

    I guess, I'm planning on getting my salt to 1.023 than see where my dkh is at that point. I have to assume it will raise with the high concentrate of salt I'm adding... as well as my Calcium.

    I'm kind of baffled on this...the only thing I can think of after doing some reading/research is I used to mix my water change water and measure to 1.023 when it was cold. Estimating <70 degrees.... for sure maybe 68 or so. I did not know a few months ago temp affects SG readings.

    Do you think I can trust my readings or should I take some water in for a lfs test?

  2. #2
    Senior Member pwall's Avatar
    Join Date
    Nov 2004
    Do you know anyone else in your area with a pinpoint SG meter ? Or perhaps a LFS ?

    49.5 on the pinpoint meter is equal to 1.023, which is where I keep my SG at in my tank.
    If your meter is saying 30, yet another meter disagrees, obviousily one of them is wrong and you'll need to determine which one.
    Ottawa (Orleans), Ontario
    Yahoo IM: pwallnfld

  3. #3
    Join Date
    Feb 2007
    I purchased both the Salinity and PH Pinpoint monitors and they are working well. They don't need to be temp adjusted. That's built in. I find it takes a few minutes with the Salinity probe in the tank for it to settle down. Try waving it in the water a bit until it temp adjusts and settles out. I have the PH running full time in my sump before the refugium. You mentioned calibrating it so that shouldn't be an issue unless they sent you contaminated fluid (which I doubt). The main reason I can think of for reducing salinity is having your skimmer set too high (watery - thus removing salt water) which is replaced by your top off system (is yours auto?). All that being said I brought mine down to the LFS to test it to be sure. You may want to as well :confused-

  4. #4
    Senior Member ALRHA's Avatar
    Join Date
    Sep 2003
    IMO, stick with a Refractometer. I have used the pinpoint and found that it is not very reliable unless you calibrate it often.
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  5. #5
    Join Date
    Jul 2004
    Do you have to calibrate the refractometer? What is the process? How often do you have to do it?
    90 Gal - 48x18x24
    Coralife 2x250W 10K MH 2x96W True Actinic
    Coralife Super Skimmer (Needle Wheel) 220
    TOM PS4 Filter with Auto Top-off
    2 x Maxi-Jet 900 Power Heads

    100 LBS Live Rock
    1 Six Line Wrasse
    1 Blue Chromis
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    Aquasafe RO/DI 100GPH

  6. #6
    Senior Member ALRHA's Avatar
    Join Date
    Sep 2003
    Quote Originally Posted by kooma
    Do you have to calibrate the refractometer? What is the process? How often do you have to do it?
    they should arrive calibrated, but if you want to double check it you can always just use RO/DI water or a known sample solution.
    My Photos

  7. #7
    Junior Member
    Join Date
    Oct 2006
    I had the same problem with my PinPoint SG monitor. Turns out my solution was off - really off. Once I got it calibrated correctly with another solution, I checked my original calibration fluid and the reading was so high it didn't even appear on the chart that PinPoint gives you! :rant:

    Also, I was told to put the water in a glass container and read it away from the tank and any other electrical devices.

    Good luck.

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