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Thread: Salinity Probe Response Time

  1. #1
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    Salinity Probe Response Time

    So I just purchased a Conductivity Probe. Yes I know I need to calibrate it, I should have the solution in this weekend. I placed it in the tank on the 27th and it was 12. My refractometer is at 30 (I ran out of salt when starting this new system. That's coming this weekend too) Over the next 3 days it climbed to 29. Is this how responsive these normally are?
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    Frequent Visitor rkpetersen's Avatar
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    Looks like yours is leveling off and will be ready to calibrate soon. After that it will be responsive to any acute change in conductivity, within moments. In fact they become too responsive, registering tiny changes in conductivity that you know do not actually correspond to changes in salinity, and also responding to changes in electrical current running through any adjacent power cords. Here's a typical trace from my tank, with unchanged salinity by refractometer over this period. Also notice how the much smaller scale of the graph accentuates the noise.

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    Quote Originally Posted by rkpetersen View Post
    Looks like yours is leveling off and will be ready to calibrate soon. After that it will be responsive to any acute change in conductivity, within moments. In fact they become too responsive, registering tiny changes in conductivity that you know do not actually correspond to changes in salinity, and also responding to changes in electrical current running through any adjacent power cords. Here's a typical trace from my tank, with unchanged salinity by refractometer over this period. Also notice how the much smaller scale of the graph accentuates the noise.

    Clipboard01.jpg
    Thanks. I did not see anything in the documentation that states there should be any waiting period before calibrating...Learn something new every day...

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    Frequent Visitor rkpetersen's Avatar
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    Pretty much anything but a temp probe I will wait a week before calibrating.

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    So I added severl cups of salt two days ago to bring my salinity up. Refrectometer has it at 35. Salinity probe still climbing and has only reached 32.5 as of today.

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    Frequent Contributor zombie's Avatar
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    Quote Originally Posted by MHG View Post
    So I added severl cups of salt two days ago to bring my salinity up. Refrectometer has it at 35. Salinity probe still climbing and has only reached 32.5 as of today.
    Did you match the calibration packet to tank temp before calibrating and vigorously shake out any bubbles? If not that explains the difference. If you did, is your refractometer calibrated?

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    Quote Originally Posted by zombie View Post
    Did you match the calibration packet to tank temp before calibrating and vigorously shake out any bubbles? If not that explains the difference. If you did, is your refractometer calibrated?

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    Thanks Zombie. I was not pointing out the issue with any differences with my refractometer. I am waiting for my calibration fluid to arrive so I have not calibrated that yet. I was raising the issue with the fact that it has taken days for the levels to go from 12ppt to 30ppt. And it is taking days to go from 30ppt-35ppt.

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    Frequent Contributor zombie's Avatar
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    Quote Originally Posted by MHG View Post
    Thanks Zombie. I was not pointing out the issue with any differences with my refractometer. I am waiting for my calibration fluid to arrive so I have not calibrated that yet. I was raising the issue with the fact that it has taken days for the levels to go from 12ppt to 30ppt. And it is taking days to go from 30ppt-35ppt.
    Took my system 12 hours to get 95% of the way and took another 4 days to completely settle out. Yours is a bit longer than typical but is still within reason IME.

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    Copy. So since it is said you can use your salinity probe to shut down your ATO if there is an issue, will this thing at some point be responsive within hours, minutes or even seconds? Or is it always this slow?

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    Frequent Contributor zombie's Avatar
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    Quote Originally Posted by MHG View Post
    Copy. So since it is said you can use your salinity probe to shut down your ATO if there is an issue, will this thing at some point be responsive within hours, minutes or even seconds? Or is it always this slow?
    Its responsive within a few seconds. The thing that is happening to you right now is there is a film building on the glass from the tank water that affects the readings but takes a bit to build up. Once the film is set on the glass the readings stay consistent.

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