PDA

View Full Version : Calibrating an Apex salinity probe


RPatsula
09-21-2012, 02:38 PM
Hello I purchased and apex salinity probe but they did not have any calibration solution. I'm wondering if it is possible to make up your own calibration solution or if there's a place in Edmonton where I could pick up some.

Thank you
Rick

sphelps
09-21-2012, 02:58 PM
Best solution is this but not sure if you'll find it locally
http://www.jlaquatics.com/product/pp-pcssa/American+Marine+Pinpoint+Salinity+Calibration+Solu tion.html

You could use saltwater provided you're confident on another device to measure it's salinity/SG however you will be introducing some kind of error but who knows if it'll matter. Pretty sure 53mS = 1.026 SG @ 25C

Otherwise perhaps someone has some fluid they could lend you.

Enigma
09-21-2012, 03:12 PM
In all honesty, the conductivity probe is problematic at best. It isn't a good tool for accurate measurements of salinity, due to its extremely sensitive and fussy nature: even when calibrated.

That doesn't mean that it can't be useful, though. It is very good at illustrating big swings in conductivity, and thus salinity.

Here's my chart for the last seven days:
http://i1035.photobucket.com/albums/a435/Iasgair/conductivity_zps38f4f21d.gif

As you can tell by looking at the chart (it is too bad it doesn't go back farther than seven days), something went wrong on the 13th of this month: which resulted in a significant dip in conductivity.

I got home from work on the 13th to discover that for some reason (as yet undertermined), my ATO over did it. It didn't over pump enough to trigger the emergency float switch, but it definitely pumped too much water in. I let evaporation return the salinity to "normal."

You can also see that something kind of funny happened on the 17th (I was what happened ;)).

Relative consistency and patterns in the graph is what really matters. I wouldn't get too concerned about the actual numbers.

With that in mind, I think it is perfectly okay to use it uncalibrated for now. You are always going to need your refractometer to get a true salinity/specific gravity reading. I've ordered my calibration solution from J&L and GoReef in the past.

sphelps
09-21-2012, 03:38 PM
Looks pretty good to me Shelly, what's so problematic about it exactly? It's actually pretty stable, just the resolution is misleading. Set your ATO to activate less frequently and it'll look a little better.

My conductivity probe works great

Enigma
09-21-2012, 03:44 PM
Looks pretty good to me Shelly, what's so problematic about it exactly? It's actually pretty stable, just the resolution is misleading. Set your ATO to activate less frequently and it'll look a little better.

My conductivity probe works great

The 18th, 19th, and 20th are what I expect to see on the graph. I consider anything else unsatisfactory. :lol: Those days are pretty much bang on, as the degree of temperature fluctuation I allow in the tank has an effect on conductivity.

What probe are you using? The Neptune probes seem to have issues remaining calibrated, and they are affected by microbubbles and debris quite badly.

Enigma
09-21-2012, 03:50 PM
As you can tell by looking at the chart (it is too bad it doesn't go back farther than seven days), something went wrong on the 13th of this month: which resulted in a significant dip in conductivity.


I just got a helpful PM to change the "end date" to see a different date range. Apparently that's an ability that I previously overlooked!

sphelps
09-21-2012, 04:45 PM
I use profilux

RPatsula
09-21-2012, 10:34 PM
thanks for everyones input. I called around and was able to get a bottle of calibration solution at mf LFS. if anyone else needs some BigAl's has one bottle left...lol.

rick