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Thread: PM2 Salinity Readings Raise With Temp

  1. #1
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    PM2 Salinity Readings Raise With Temp

    Last week I changed tanks from a normal 125g to an RSM e260 AIO style tank. I've been having issues trying to keep the tank cool but thats nothing I'm concerned about in this question. I noticed that as my temp raises, my salinity readings raise just as much, when temp falls, salinity probe readings fall as well. The two graphs look almost identical. My temp range is typically 79-80 (heaters are set at 78).
    I've tried to make sure my salinity probe line isnt close to anything else, and it's not near my temp probe which is on the other side of the tank.

    Is this normal? Any way to fix it or is it just what happens with conductivity probes. I've calibrated the salinity probe a couple of months ago and it's.....sort of accurate. It typically says 35 ppt when the tank is actually 1 ppt lower. I dont mind that so much, as long as it's stable.

    Screen Shot 2017-10-15 at 8.12.10 PM.png

  2. #2
    Frequent Contributor zombie's Avatar
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    You can fix that with temperature compensation. Start at a value of 2.2 and adjust from there. If cond rises with temperature increase the number by 0.1 a day at a time until it's mostly stable (no more than 0.1 to 0.2 ppt variation per degree F) if cond lowers as temp rises, reduce by 0.1 each day until stable.

    You might be an engineer if...You have no life and can prove it mathematically.

  3. #3
    Master Control Freak RussM's Avatar
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    Note that in order to use temperature compensation, you must have a temperature probe connected to the PM2.
    Please do not send me PMs with technical questions or requesting assistance - use the forums for Apex help. PM me ONLY if the matter is of a private or personal nature. Thanks.

  4. #4
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    Quote Originally Posted by RussM View Post
    Note that in order to use temperature compensation, you must have a temperature probe connected to the PM2.
    Should I just take my main temp probe and plug it into the PM2 or get another temp probe?

  5. #5
    Frequent Contributor zombie's Avatar
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    Quote Originally Posted by splix View Post
    Should I just take my main temp probe and plug it into the PM2 or get another temp probe?
    You can do either way. Moving requires you to also change all code that references the temp probe, but is free. Getting a new one lets you keep your code intact and gives you a backup in case the main one ever fails.

    You might be an engineer if...You have no life and can prove it mathematically.

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