New Apex Question

[Carz]

I got my new Apex hooked up and I did the calibrations as per instructions. The readings just dont match up. If I take the PH probe and place it back in the PH solution 7. it reads below 7 and the same for 10. Should it not read exactly 7 and 10?? The salt also reads high as well. I checked my salinity with my calibrated milwaukee digital reader and salt is perfect and my eye refractometer reads perfect as well. Thoughts???

 

[Brett S]

How much of a difference are you talking about? If it’s reading 6.9 in the 7.0 solution then that’s normal and within the expected margin of error. If it’s reading 5.5 in the 7.0 solution then something is wrong.

 

[vetteguy53081]

+/- 1 is acceptable

@SuncrestReef

 

[Carz]

PH is reading 9.57 in the 10.0 solution.....

 

[Attreui]

Recalibrate it. Make sure you give it time to settle. It will take a few mins. Rinse the probe off between going from the 7 to the 10 in fresh water. If after doing it a second time it still wont hold, it is probably a defective probe.

I have found the Apex salinity to be hit or miss when it comes to calibration. Calibrate it, and then see where it hits. Check it with a refractometer. There is a field in the salinity probe section (in the WEB interface, not sure if it is in apex) to allow an offset. you can put positive and negative numbers in there to tweak the calibration. It is not 1:1 which means if you are reading 32 and your water is 35 you don't just stick a 3 in there. Play with the numbers until you get the right reading. I have found that it holds correct once you do that and reads properly. I check it against a refractometer every few months just to see if it needs tweaked. If you get a really off the wall reading, you need to pull the probe out and let it sit in the air for a few mins. The reading should drop down to 0. put it back in and turn it so any bubbles come out and it should come back up right. Its a process.

 

[DC Reefer]

Also when I calibrate PH probes I move the probe around in the solution until it settles - for me gets a more accurate calibration.

 

[Alchameth]

Also when I calibrate PH probes I move the probe around in the solution until it settles - for me gets a more accurate calibration.

+1

 

[Butcher333]

Also make sure the temp of the calibration solution matches the tank water. This could be the reason. The salinity probe fluctuates as well. This reminds me that I need to get some calibration solutions and another temperature probe. I want to recalibrate mine. I don’t think I properly calibrated everything the first time. My PH, ORP, and Salinity all rise during the light period and as the temp fluctuates a couple degrees.

 

[Carz]

is there a way to change the salinity to read SG

 

[Attreui]

is there a way to change the salinity to read SG

Unfortunately not. It will read in ppt or conductivity.

You can use an online converter or just look into a refractometer if you need to convert. Most refractometers have both side by side.

 

[Carz]

Not a big deal, just been using SG for so many years. I can change.

 

[Reefs and Geeks]

I just got my apex set up a few weeks ago as well. For the salinity probe, be sure to go into the advanced configuration and turn on temperature compensation (TC) and set the % to 2 to start. Will give you MUCH more stable readings as the conductivity changes with temp. Then calibrate it again. Before I did that, my salinity graph looked like my temp graph, going up and down daily. Now it's stable to within +/- 0.1ppt.

Also a trick I read and has worked for me to calibrate it is to just calibrate it directly in your tank water vs conductivity standard. Just use your refractometer to make sure your salinity is at 35ppt, than when you perform the calibration, simply stick the probe in the tank water for calibration.