ORP daily fluctuation

[OREGONIC]

Posed this on my local forum but figued i would share and question here aswell.

What is a standard daily ORP fluctuation on a tank that does not run ozone? I have only had an apex for a few weeks and my tank runs 90ish at night and 330ish during day. I have an ATS running opposite schedule of my tank lights and run my skimmer around the clock. Whats weird is my light dont turn on till 1130 am and hit peak at 130 but my ORP starts to rise at 7 am which is way before the lights come on. Is this a mormal fluctuation and timing, seems consistent so im not to concerned.

Here is my comparison graph of PH to ORP. There was one spike in my PH when i first added my dosing pumps to the Apex due to an error in my coding and the pump ran a little to long. But other then that PH seems to only flucate about .12 per day which seems fairly normal from what i have read. The ATS is off for the 6 hours of my peak lighting and then on for 18 hours. I have also attached a photo of my light cycle. Everything in the tank looks happy except for a few acans which have never really done well for me. All water parameters seem fine Alk 8.2-8.5, cal 425, nitrates just under 10 ppm and have slowly been dropping over the last month or so since ATS has started to really take off. I did buy the apex used from someone on the forum and the probe was used. He did have it in a tupperware with tank water in it and was never out of the water for more then 5 minutes. I do have the probes located in the aio upper sump chamber of my E-170 and not in the lower sump that i added but i do not believe that would effect the reading. ORP seems consistent day to day but just seems like a large swing from what i have read online.

 

[LobsterOfJustice]

Yeah, that seems like a tremendous swing. Are you doing any other kind of dosing for nutrient control or feeding? It doesn't look like the ORP swings are exactly tied to a daily cycle. I know my level crashes when I feed certain foods.

 

[OREGONIC]

Once a day a feeding of LRS Reef Frenzy. Small piece about the size of a dime in diameter. I dose 7ml of fuel 2 times a week. I would think the probe is possibly bad but the swing is to consistant day to day. Using BRS 2 part and each part is dosed every hour and a half with 45 min between alk and cal. Im stumped and can not find anything online referancing a similer swing.

 

[Mal11224]

Typically, you should see you PH go up if your ORP goes down and vise versa if all is well in your tank. So, ORP usually rises at night as your PH falls. You ORP fluctuation is very large. Did you calibrate your probe? Amino acids and other high protein foods will cause the ORP to drop but not like what you've been experiencing. All of your numbers look good. ORP is tricky and I'm not too sure how important it really is but can be a concern with the way your levels fluctuate. I think as long as your more important parameters such as Alk, calcium, PH, temp and salinity are stable, you should be fine. Would not put too much emphasis on ORP.

 

[OREGONIC]

Typically, you should see you PH go up if your ORP goes down and vise versa if all is well in your tank. So, ORP usually rises at night as your PH falls. You ORP fluctuation is very large. Did you calibrate your probe? Amino acids and other high protein foods will cause the ORP to drop but not like what you've been experiencing. All of your numbers look good. ORP is tricky and I'm not too sure how important it really is but can be a concern with the way your levels fluctuate. I think as long as your more important parameters such as Alk, calcium, PH, temp and salinity are stable, you should be fine. Would not put too much emphasis on ORP.

I understand that ORP is not something that is fully understood and it should be looked at as more of a pattern. The pattern that my tank has seems stable in the sense that it is consistent day by day, but the swing seems huge and the exact opposite of when the highs and lows should be showing. I did not calibrate the probe, i ordered the 400 calibration solution, along with solution to calibrate ph probe, prior to picking up the apex from a local reefer who was in the process of taking down his tank. When i picked up the apex after waiting for his livstock to sell i was going to calibrate the ORP probe but found out the producer required a completely different set of solutions to do so. I also read that the apex does not need the probe calibrated due to not looking for 100% accuracy, more into the pattern. I did wipe the apex of all data, wanted to start fresh when setting it up. Is there an easy way to calibrate the probe that i just have not stumbled across? Should i just purchase a new probe? Is it possible the the former owner of the apex calibrated the ORP probe incorrectly, false high and low calibration, and when I wiped the apex of all the data the bad calibration stuck for some reason? Not to concerned just puzzled.

 

[Mal11224]

I understand that ORP is not something that is fully understood and it should be looked at as more of a pattern. The pattern that my tank has seems stable in the sense that it is consistent day by day, but the swing seems huge and the exact opposite of when the highs and lows should be showing. I did not calibrate the probe, i ordered the 400 calibration solution, along with solution to calibrate ph probe, prior to picking up the apex from a local reefer who was in the process of taking down his tank. When i picked up the apex after waiting for his livstock to sell i was going to calibrate the ORP probe but found out the producer required a completely different set of solutions to do so. I also read that the apex does not need the probe calibrated due to not looking for 100% accuracy, more into the pattern. I did wipe the apex of all data, wanted to start fresh when setting it up. Is there an easy way to calibrate the probe that i just have not stumbled across? Should i just purchase a new probe? Is it possible the the former owner of the apex calibrated the ORP probe incorrectly, false high and low calibration, and when I wiped the apex of all the data the bad calibration stuck for some reason? Not to concerned just puzzled.

It is quite possible that the probe is defective or really just needs a calibration. I find it hard to believe that the fluctuation you are getting on a daily basis is correct as your tank parameters look good. You may want to invest in another probe if you feel it's necessary. The calibration process is expensive. You may have seen the video below from BRS TV. When I first hooked up my apex, my probe took nearly a week to calibrate by just setting it in my sump. So, there wasn't a particular solution to use, just set it in the sump and let it adjust. Do you have a stand alone PH probe? I would use it to test the accuracy of your apex PH probe. just to make sure. So, a few things to consider. Maybe let the ORP probe sit in your tank for a while and see if it adjusts to your water or just get a new one.

 

[Randy Holmes-Farley Verified Community Expert]

Is the ORP probe exposed to bright lights? Algae growth on it will impact ORP measurement.

Where is it in relation to where the pH is measured?

 

[OREGONIC]

I have the Neptune probe rack in the back chamber of my AIO e170. I have added the red sea lower sump to my tank but the probe rack seemed better placement as it was a long way from the heater and wanted a more accurate reading in temp. The back chamber of the AIO is covered by a black piece of glass, I attached a photo below that shows the chamber and how it is covered and a photo of the glass flipped up to show placement. No visable algae anywhere on the probe.

 

[Monkeynaut]

What salt do you use?

 

[OREGONIC]

Aquaforest probiotic. Total system volume is about 50 gallons and i do a weekly sometimes bi weekly water chage of 5 gallons. All water that enters my tank is done with RODI water that reads 0 TDS.

 

[Randy Holmes-Farley Verified Community Expert]

I'm surprised the swing is that large, but I doubt it is an indication of a true problem that needs fixing.

 

[James Kanouff]

I'm surprised the swing is that large, but I doubt it is an indication of a true problem that needs fixing.

I second.. orp probes can be hit or miss i think. Try moving it to a different place in the system for awhile. Immediately after I feed or WC my ORP fluctuates. Other wise, fairly stable over 24 hours. I have found a new probe shows same average swing over 24 hrs, but a significantly different number value. Say one reads 375 other 275 at the same time both showed a 30 point swing after cleaning and 48 hours to settle after said cleaning. All I use ORP for is monitoring my sulphur denitrator now. Never found another good use for them. Likely a key part of using a OZONE system initially maybe as well but i don't have feed back on that personally. Randy might.