My orp is reading 126 is this right?

[reefyguy]

This seems low?

[Macimage]

Yes, that is very low.

Are you sure it's correct? If it is, you should do a water change to improve the number.

If the orp becomes too low, there is not enough oxygen for the fish to live.

Joyce

[Billybeau1]

That is absolute bunk. I'm sorry Mac, but lets get the facts. :(

reefguy, your orp level has little to do with the oxygen level in your tank.

A water change will not improve the number.

More likely it is a new probe and needs some breaking in. Most ORP probes need a few days to settle in. It will slowly start to rise over the next couple of days and will settle in a week or so.

Make sure to read Randy's articles on ORP and what it means before you take any corrective action.

Good luck. :)

[Macimage]

Eight years ago when I was a newbie my orp dropped under 100 and all my fish died. Just going on that experience.

A water change and more oxygen would have helped them.

Sorry if I gave any info that is incorrect.

Joyce

[moonyguy]

I would agree. You might need to recalibrate and let the probe settle in for a week or two before you can take a reading. I started around the same level now it runs about 350-400. I recalibrate about once every 4-6 months. Just wait it out your numbers should climb. :)

[Billybeau1]

Thats ok Joyce. It's likely you had a major problem that killed your fish but ORP is not really a good indicator of the oxygen level is in a tank.

:)

[GeoffM1968]

Reefguy, I am not an expert but have done a lot of reading on this and referenced a couple good articles on this:

http://www.reefkeeping.com/issues/2004-05/rhf/index.php
http://www.reefkeeping.com/issues/2003-12/rhf/feature/index.php
http://www.canadiankoiandpond.ca/articles/article13.html

For my tank and local water properties, my ORP ranges 100 to 150 which is acceptable range for my water conditions. When I drop below 100 for my water conditions (watched values throughout day for months on new tank and three years on Koi Pond), I know I have waited too long for a water change, over feeding, or something has died. In addition when I measure my RO/DI water after adding Tropical Marine Pro Salt using MaxiJet to mix for 24 hours, it is in the 105-110 range consistently.

Trying to achieve the magical 300-350 which many say you should have just does not work for my water conditions which everything else shows is in great condition. I could install ozone equipment and achieve this magic number but I do not have the need at this point and may not really improve my water quality.

I use the ORP reading to look at relative hydrogen (manual calculation rH=((ORP+205)/29.58)+(2*pH) ) which factors pH which has been shown to have an inverse relationship to ORP (Higher pH the lower the ORP). An rH in range 27-35 rH has been shown to be acceptable range. What you need to do is compare your readings over time and what your observations of your tank and may also compare to someone using same water source and preparation methods (RO/DI, Salt, additives, GFO, etc.) to gauge the acceptable range for your tank. Then use this to gauge if you have an issue which may need resolved (water change, over feeding, dead critter, etc.). You should use other means to gauge oxygenation of your water column as that is only a part of ORP.

Again, I am not an expert but what I have found looking into my early frustrations with low ORP compared what others are saying I need to be at for my tank. As the good articles indicate, it all depends... instead it is best to measure your ORP over time using your observations to track the trends for your water properties. When you have identified your trends, you can have an early warning sign of something which may be amiss in your tank.

[unhpian]

ORP is a big pet peeve of mine. IMHO, it has no business being used in aquariums - too many people don't fully understand it, and use it to justify adding oxidizers that they don't need. You shouldn't be using ORP to judge the health of your system - too many things can interfere with it and give you bogus readings.

[bertoni]

If oxygen might be the problem, then an oxygen kit is more appropriate than an ORP meter for testing. Low ORP can correlate with a lot of conditions. The link on ORP that was posted is good to read.

There are significant issues in measuring ORP, at least with hobbyist-level equipment, and I agree that a value from a new probe tends not to be useful.

ORP can change for a number of reasons, and many of them are bad things to have happen in a tank. Once the probe has settled, a large ORP change might be a sign to look for troubles.

[reefyguy]

update: i am at 265 right now

[ReefEnabler]

do you dose anything??? certain things might contain antioxidants that will make ORP plummet.


for example I dose vitamin C and it makes my ORP plummet from 415ish down to around 50 for a couple hours. No ill effects. Nobody is quite sure why VC has such a drastic affect on ORP, but it is an antioxidant so some drop is expected.

I do not run ozone, but I think my skimmer and flow are what keep the ORP high.


edit, I've never used the rH calculation before thats mentioned above. With ORP around 420 and pH around 8, that makes my rH around 37 or slightly higher than the 27-35 range that Geoff mentioned.

[bertoni]

265 seems reasonable. I wouldn't worry.

[Malenurse]

I have a handheld ORP meter. How can I get the probe to "settle" since it's never continuously underwater?

[bertoni]

Hmm, interesting question. You might have to make do with what readings you get, and worry only about any changes. I think that's the best approach even with a monitor, unless ozone is being run.