Apex salinity and ORP probe woes

reefinmike

New member
Hey all, I made the jump a few weeks ago to the new apex, literally the night before they released the EL model which is $300 cheaper without the salinity, orp and VDM- all things I really didn't need. I convinced myself to be happy with the purchase as having a salinity probe would be one more layer of protection, the ORP would be kinda nice to be able to see and I can sell my vdm module.

Initially my ORP probe started out reading around 170 and has since slowly risen to 415 where it sits today. I do notice the orp drops every day shortly after feeding but I'm curious if this huge change over three weeks is anything to be concerned about in terms of proper calibration/interference. I do realize that ORP readings vary tank to tank and should be taken with a grain of salt. One important thing to note is that I discovered a turbo snail had died about the time I added the probe and mostly rotted away in the tank. I suspect the flatworm exit treatment two weeks prior killed the snail.

The salinity probe is my main concern. I have only seen consistent readings for about 24 hours. When I initially calibrated it, I did not do a lot of research and simply followed the prompts for calibrating and dipping it into the solution warmed to tank temp. It initially read around 35 then quickly rose to 100 over the course of 4 days. After watching several YT videos on the subject I found the key to proper calibration was calibrating in the same area as your temp probe, isolating the cable from other electronics especially ballasts as well as fully emerging the probe in solution purging all air. I did this using one of the screw cap jars used to keep probe ends wet when not in use and turning the probe upside down gently shaking all air out. between calibrations I cleaned the probe in RO/DI and allowed it to dry for two days. After the second calibration it started at 32.5 and rose up to about 36 over 24 hours. it stayed fairly stable but kept creeping up bit by bit so out of curiosity I shook the probe out and put it in 35ppt refractometer calibration solution. It shot up to 40 and stayed there. I rinsed the probe again and let it dry and attempted recalibrating using the unused solution that I carefully sealed off. I know this isnt proper but I had to try again before ordering more damn calibration solution. It started at 36.25 and over the past couple days has risen to 38. What am I doing wrong? this is driving me crazy. When do I contact apex and raise a fuss?

The salinity probe cable comes straight out from the apex head and does not come within 12 inches of any other wires or electronics. I keep it in my "refugium" area which has zero micro bubbles. During calibration I turn off all ballasts as well as the koralia in the fuge area where I calibrate. My only other salinity reference is my BRS refractometer which is calibrated with same temp 35ppt cal solution. The refracto shows my tank to be a stable 35ppt. I have not done any water changes, my system holds approx 110g of water and the ATO never drops in more than 4 ounces of water at a time. The skimmer removes maybe 8 ounces a week and I have added 16 grams of NaCO3 since adding the probe.
 

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I would say your ORP is fine. The sail probably was the reason for the low initial readings and as that cleared up it would climb. Normal to see a dip after feeding, etc.

As for your Salinity Probe, its whacked out! Call Apex and if they cannot help you, I am sure they will replace it. The two times I have called and others where I have used their email support to deal with my own "œuser error" issues, then have been great.


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Thanks for the quick responses, Kinda what I figured as the ORP goes, I'm just a bit surprised it has more than doubled and is now nearing what people consider a maximum safe level when using ozone.

Really not sure what I could be doing wrong with the salinity probe. the second calibration was done as properly as possible as well as the third aside from the fact I used the remaining solution from the calibration a week prior. I sealed the small cut in the packaging very well with clear packing tape. again not ideal but I'll go broke chasing this salinity probe problem with $3 calibration packets. Is there any safe every day thing to verify the probe with? like should it be ok to put in RO/di and expect it to read 0ppt? any idea why my 35ppt refractometer calibration solution caused it to jump up to 40 and stay there once back in tank water?
 
Do not use refractometer solution to calibrate a salinity probe. The solution has to be for use with a probe. I use the pinpoint brand to calibrate my probe. The salinity probe is actually a conductivity probe. The salinity value is a calculated value. If you are confident in you refractometer you can calibrate your probe using the value of your tank from the reflectometer as one of the cal point when the probe is in the tank. Also it is not unusual for new probes to drift when first put into use.
 
Thanks for the quick responses, Kinda what I figured as the ORP goes, I'm just a bit surprised it has more than doubled and is now nearing what people consider a maximum safe level when using ozone.

Really not sure what I could be doing wrong with the salinity probe. the second calibration was done as properly as possible as well as the third aside from the fact I used the remaining solution from the calibration a week prior. I sealed the small cut in the packaging very well with clear packing tape. again not ideal but I'll go broke chasing this salinity probe problem with $3 calibration packets. Is there any safe every day thing to verify the probe with? like should it be ok to put in RO/di and expect it to read 0ppt? any idea why my 35ppt refractometer calibration solution caused it to jump up to 40 and stay there once back in tank water?

ORP probes take a week or more to settle in and they start out low and will rise over the course of a week or two until the finally settle in. Once settled in, ORP will change from day to night by 20 or more points.

The salinity probe should be allowed to sit in the sump for a week or so before calibrating for best results. It is absolutely critical that the probes be placed in an area devoid of microbubbles and ideally in a dark place so algae doen’t grow on them. Any microbubbles that accumulate in the probe tips will result in inaccurate readings that change constantly. Also, it’s important that the calibration solution be the same temp as the tank water where the temp probe is located. I float the calibration solution bags in the sump prior to calibrating to insure the temp compensation is accurate. Lastly, you can calibrate your probes with refractometer calibration solution and expect accurate results just like you can’t calibrate your refractometer with probe calibration solution.
 
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