Calibrate Good Times, Come On!

Floating the calibration solutions in the tank

Manufacturers recommend that you calibrate electronic probes frequently. Once every month or two is recommended. This helps keep the probes accurate, and allows you to get an idea of when its time to change the probe. A pH probe is generally good for 12-18 months.

My pH probe is an American Marine Standard Grade pH probe. It is connected to my Digital Aquatics Reefkeeper Elite. I have the probe in my sump to provide real time pH readings.

 The Reefkeeper Elite uses a two-point calibration. For a reef tank, we will be monitoring levels in the higer range, so we will want to calibrate with the 7.0 and 10.0 pH solutions. Today, I used the single use packages from American Marine. These packages are sealed until use, and then discarded. While large bottles may be more economical, the larger bottles pose the risk of leaking or evaporating, which could affect the reading; you probe would be calibrated incorrectly.

7.0 solution

You'll want to get the temperature of your solution correct. The American Marine solution is 7.0/10.0 at 77 degrees F. My aquarium water is set to 77 degrees, so I just tossed it in the aquarium and let it sit for 15-20 minutes (probably longer).

I'll cover the steps for the Reefkeeper Elite. Other systems will vary, so consult your user guide. The process is similar...

First, access the RKM-SL1 module (You may also have an SL2).
[ IN ] > SL1 > ph > [ ENTER ]

SL1 > pH

The first set point is defaulted at 10.0. You can adjust this if needed, or if your are using other pH solutions. Assuming the probe is already connected, rinse the end with some RO/DI water and put the pH probe into the corresponding solution (in this case, 10.0 pH). The Raw Date field will begin to fluctuate and count up or down. Wait several minutes until it does not move anymore, or until it is relatively stable. I left it for 10 minutes.

Target and Raw data

Once the Raw Data numeral no longer changes, select NEXT and then click on the [ENTER] button. Repeat the process using the next solution (in my case, I used the 7.0), rinsing the probe before putting it into the solution. Select SAVE and click [ENTER] to save the settings. The pH is now set. I left the probe in the 7.0 solution as you can see... Perfect. Rinse the probe in some RO/DI water before putting it back into the tank.

It's in the 7.0 solution...

Verify the probe is reading correctly; test with a secondary kit if you must. Boom, you're done! Confidence is bliss...