High orp

underwaterdan · Jan 26, 2016

So I hooked up my orp probe a while ago but never turned the orp function on in my Apex. Anyway my orp is at 460. Is that a calibration issue or can that be a realistic number that I need to work on?

Randy Holmes-Farley · Jan 26, 2016

Unless you are using ozone or other oxidizers, ORP, whether real or in error, is never too high and high ORP is never a problem.

Yours may be real, or ORP might be as low as around 200 mV.

I discuss ORP in detail here:

ORP and the Reef Aquarium - Reefkeeping.com
http://reefkeeping.com/issues/2003-12/rhf/feature/index.htm

from it:

Recommendations for ORP

ORP is an interesting, if complicated, measure of the properties of water in a marine aquarium. It has uses in monitoring certain events in aquaria that impact ORP but may be otherwise hard to detect. These events could include immediate deaths of organisms, as well as long term increases in the levels of organic materials. Aquarists that are monitoring ORP in an aquarium, and are doing things that otherwise seem appropriate for maintaining an aquarium (such as increasing aeration, skimming, use of carbon, etc.) may find monitoring ORP to be a useful way to see progress.

ORP measurements are very susceptible to errors. Aquarists are strongly cautioned to not overemphasize absolute ORP readings, especially if they have not recently calibrated their ORP probe. Rather, the most useful ways of using ORP involve looking at changes in measured ORP.

Some aquarists use oxidizers to raise ORP. Those additions may be of benefit in some aquaria, and they may be beneficial in ways that aren't demonstrated by changes in ORP alone. I've never added such materials to my aquarium. In the absence of convincing data otherwise, such additions seem to me to have more potential risk than is justified by the demonstrated and hypothesized benefits.

underwaterdan · Jan 26, 2016

Thanks very very much randy. I plan to use it as a Guage to see changes in my overall tank. I am going to read that page in detail just to get myself familiar. Thanks again

Randy Holmes-Farley · Jan 27, 2016

You're welcome.

Happy Reefing.

Jesmann · Jan 27, 2022

I know this is a old post but I'm wondering if someone could chime in. My ORP typically is around 380-420 on average over the past 3 years . After installing my UV sterilizer, now iv been creeping up over the past 2 weeks it hit as high as 460 today. I turned my UV off for 6 hours and it has now dropped to 435.

ORP probe is in a 180gal sump in the fuge section with the rest of the probes.

UV is installed inline of return pump. the UV unit is a 80w aqua ultraviolet and is running around 900GPH flow threw it. Im currently looking into new return pumps to up my flow to around 1200-1300GPH.

Doing some reading I'm seeing anything over 450-500 is harmful in a mixed reef tank. Should i program the UV so it shuts off if ORP hits 450.

Randy Holmes-Farley · Jan 28, 2022

I do not think a UV is able to cause problems by raising ORP too high, at least as long as it is not excessively sized for the aquarium.

I don't think that ORP itself is typically the concern, but rather the highly oxidizing species that are often causing high OPR, and I do not think a UV generates these to the degree a system like ozone can.

I've never used a UV, nor looked into what happens when they ar etoo large so maybe some UV users can respond.

Here's an article of mine on ORP itself and what it means:

ORP and the Reef Aquarium - Reefkeeping.com

Jesmann · Jan 29, 2022

I heave read your article.

I have a 80w aqua ultraviolet on a 580-620ish actual water volume system. So I think sizing is on point. Should I be worried about orp at all? At level should I consider "to high". Would feeding more help lower orp?

Randy Holmes-Farley · Jan 30, 2022

Jesmann said:
I heave read your article.

I have a 80w aqua ultraviolet on a 580-620ish actual water volume system. So I think sizing is on point. Should I be worried about orp at all? At level should I consider "to high". Would feeding more help lower orp?

I personally would not be worrying about ORP in this scenario.

Lowering it artificially isn't necessarily the same as not raising it in the first place, but vitamin C will crash ORP if you add it.

Jesmann · Jan 31, 2022

Funny you say this I stopped doseing vit c when it started going up. Very interesting. I used to daily dose vit c.

Randy Holmes-Farley · Jan 31, 2022

Jesmann said:
Funny you say this I stopped doseing vit c when it started going up. Very interesting. I used to daily dose vit c.

Maybe the ORP reading is offset low, and it is slowly getting back to normal.

Jan86 · Nov 11, 2023

Randy Holmes-Farley said:
Unless you are using ozone or other oxidizers, ORP, whether real or in error, is never too high and high ORP is never a problem.

Yours may be real, or ORP might be as low as around 200 mV.

I discuss ORP in detail here:

ORP and the Reef Aquarium - Reefkeeping.com
http://reefkeeping.com/issues/2003-12/rhf/feature/index.htm

from it:

Recommendations for ORP

ORP is an interesting, if complicated, measure of the properties of water in a marine aquarium. It has uses in monitoring certain events in aquaria that impact ORP but may be otherwise hard to detect. These events could include immediate deaths of organisms, as well as long term increases in the levels of organic materials. Aquarists that are monitoring ORP in an aquarium, and are doing things that otherwise seem appropriate for maintaining an aquarium (such as increasing aeration, skimming, use of carbon, etc.) may find monitoring ORP to be a useful way to see progress.

ORP measurements are very susceptible to errors. Aquarists are strongly cautioned to not overemphasize absolute ORP readings, especially if they have not recently calibrated their ORP probe. Rather, the most useful ways of using ORP involve looking at changes in measured ORP.

Some aquarists use oxidizers to raise ORP. Those additions may be of benefit in some aquaria, and they may be beneficial in ways that aren't demonstrated by changes in ORP alone. I've never added such materials to my aquarium. In the absence of convincing data otherwise, such additions seem to me to have more potential risk than is justified by the demonstrated and hypothesized benefits.

Hello! Im having this problem where my orp is ramping up like grazy every mornig it spikes like this(blue dots). Waterchages are the only help i have found that keeps it from spiking too much (red dot). It can go up like from 300mv to 400mv in 3 hours and then my corals look very stressed. Acros shows filaments andHammers mouth open etc.