ORP calibration kit?

[dread240]

Ok, so I've wanted to calibrate my orp probe, but the cheapest I could find the unobtanium powder was like 40-50 bucks shipped for just that, so I kind of left it be.

I did however stumble across this.

http://www.freshwatersystems.com/p-...um=Feed&utm_campaign=Product&utm_term=ORP-BUF

It's a 2 point test kit for orp probes, and mixes up one at +92mv and one at +265mv. It doesn't list what's in it though

Now reading http://www.reefcentral.com/forums/showthread.php?t=2205934 they stated that they did mix up the proper solutions for the orp calibration (using that quinowhatsoburger compound) and that his readings showed +91mv for the low end and +267 for the high end.

Is it safe to assume this is a neptune orp calibration kit that I've found for a decent price?

 

[FullBoreReefer]

$2.99 per calibration...

http://www.bulkreefsupply.com/catalog/product/view/id/707/

This is 400 fluid, a lot closer to what our tanks run IMO

 

[dread240]

400mv ORP is not the proper calibration solution for an apex with an orp probe, the apex requires a 2 point calibration kit so that it can calibrate the scale and the offset of the probe

 

[FullBoreReefer]

Can't you change the fluid used like in the ph calibration?

If not use this. Still $2.99 per 53ms and 447ms

Http://www.bulkreefsupply.com/neptune-systems-conductivity-calibration-solution.html

 

[dread240]

Nope, those are conductivity, not ORP calibration solutions.

Believe me, neptune did NOT make ORP easy to calibrate on their controller

This was linked by neptune before as the orp calibration kit http://www.pulseinstruments.net/orp2pointcalibrationkitwithquinhydronehighlyaccurate.aspx

There you can see clearly and it's labeled that this kit uses quinhydrone so you know for a fact it's correct.

The kit that I found is half the price of this kit, and according to previous research should be the right +mv values for the 2 point calibration, it just doesn't explicitly state what is in their kit

 

[FullBoreReefer]

Nope, those are conductivity, not ORP calibration solutions.

Opps you are right.

I reread the manual. Says you should never need to recalibrate for the life of the probe.

But to use that special powder if needed. Sounds interesting...lol

 

[FullBoreReefer]

Try this with the 400 solution...

http://www.reefcentral.com/forums/showthread.php?t=696645&highlight=hidden+menu

 

[dread240]

I've seen that, it really only does the offset factor though, not the actual scale

 

[FullBoreReefer]

But you calibrate the offset factor to the probe reading of a known fluid. So in theory you are calibrating to a known source. Just leave the scale as is.

There are options just not sure what else your looking for...

So go high dollar for correct kit...

Or go single point calibration...

Don't see any other options...

 

[dread240]

or if this mid priced kit is correct use it and have it done right

by others readings on the calibration fluids, it should be the correct kit for calibrating an orp probe on an apex controller, at less then half the price of other kits that have been brought up previously.

Reason they suggest not using the 400mv solution is that while yes, you can change the offset to match the 400, the scale could be completely off. 400 will read 400, but 375 may read 350, 350 could read 300, and by the time you get to 325 it could be reading 250.

Generally speaking, the trend is the most important factor, that's why they don't even mention calibrating it, but I'd like to know what I'm really reading. Right now my tank is showing 280 or so at night and 270 during the day. Those numbers are far lower then what I've seen people mention, and I've also been having issues with monti's and cannot find a cause at all. All my water parameters are testing pretty good so I'm trying to see if my "low" ORP might really be low, and I'm missing something, or if there are other factors at play.

 

[dread240]

anybody from neptune on this one?

 

[kurt_n]

Neptune doesn't normally comment on this forum. You might drop them an email at their support email address if you want a response from them specifically. My guess is that they'll just reitereate what's in the manual, but it doesn't hurt to ask.

While the 400mV solution can't be used to calibrate, you *can* use it to spot check the readings you're currently getting. If you dunk your probe in it, and you get 320mV on your display, then it's obvious calibration is in order if you want an accurate number. If you get 400mV (or close to), then I'd be apt to think your calibration parameters are good and calibration isn't going to change anything much. Just my 2cents worth. I've never calibrated any of my ORP probes, but used the 400mV solution to spot check to see when it's time to get a new one.

 

[morty]

According to a document I found from Hach, a pH 4 solution saturated with quinhydrone mixes to 265.1mV +/-5mV, and a pH 7 solution likewise saturated mixes to 87.4mV +/-5mV. These are the values the Apex looks for when calibrating (actually, 86mV and 263mV according to the Comprehensive Apex Manual), and unlike calibrating pH you can't tell the unit that you are actually using some other reference value when calibrating ORP. Whereas the kit you found does sound like it might be ok for the high end calibration, the 92mV powder may be off by enough to affect your calibration's accuracy. That's more than 5% higher than what the Apex is expecting to see, and could be worse if the 92mV powder actually mixes up on the high end of its error range.