Orp

[Mylesweaver]

I constantly monitor my orp in my piece of the reef. I was wondering who else is doing this and what are your numbers? I think there is a lot to be said about how clean your water is by monitoring this number and I don't hear a lot about it.

[HiFidelity]

high 300's into the low 400's, when I do a water change the number goes down and just before a water change number is at it's highest. That's all the observing I've made, never cared to look closer...

[d2mini]

Low 200's without ozone use.

[Gorgok]

I never have understood what this reading even means... Even wikipedia fails to explain it, with only this making any real sense: "E. coli, Salmonella, Listeria and other pathogens have survival times of under 30 s when the ORP is above 665 mV, compared against >300 s when it is below 485 mV"

Which sounds like high numbers = nuking stuff. Is that the goal or the fear in aquarium cases though?

[doctorwhoreefer]

400's here, dips to low 300's during a wc. Dips down some when adding large quantities of food.

Hey d2mini have you ever noticed any negatives when its that low? I'm assuming your tank is fairly stocked ��

[wolfblue]

Low 200's is fine. Water can be crystal clear and healthy at 230. But 400 if its a accurate number could mean the presence of secondary oxidants with ozone use. But these scientific grade probes that cost $69 seem to start drifting up as soon as you put them in the water. Nobody will really be at 400 without ozone. On top of that is the 20mV accuracy thing.

Sterilization is not what were after with ozone in salt water. Sterilization being killing some organism that could be detrimental like on wikipedia . Some small amount of sterilization does occur but most people are after oxidizing compounds that color the water. And some people want that, plus they think a very small amount of ozone aids in foam formation in the protein skimmer. So they inject the ozone into the protein skimmer and use that as a ozone contact vessel.

That last "some people" is me. I think the ozone will act as a micro flocculent, making some compounds less skimable and making some more skimable. And the overall effect is a net gain in the protein skimmer. And of course the ozone cracks some compounds to make the water whiter and that's good too.

The problem when thinking of ozone as a sterilization agent in salt water is that ozone reacts with things in salt water that result in secondary oxidants. Halides like the bromine derivatives are persistent and can and will survive long enough to get to animals. Ozone will always make these oxidants and so you want the level of oxidants low so they can contact reducing compounds before they get to the animals. Its probably true that most of the sterilizing effect seen from ozone in salt water actually come from the secondary oxidants. Very low chronic levels of residual oxidants are not easily detected by hobbyist level test kits and could result in primary health problems and susceptibility to secondary health problems for the more sensitive organisms.

So people that use ozone will always have all the effluent from any ozone contact vessel passing through a generous amount of carbon. Carbon destroys the residual oxidants and ozone so they will change the carbon frequently just to make sure. They will also keep on hand a sodium thiosulfate based dechlorinator solution. In the event something goes wrong with the system and they suspect oxidants are loose they will dechlorinate the whole system immediately.

Ozone is dangerous stuff in salt water and it does not have to be a wipeout type thing. A low level oxidant problem could be responsible for a reef where some things just don't flourish even when all the other numbers are good. But they don't know the number form a low level DPD chlorine test. Even with a good expensive oxidant test kit its hard to see oxidants in the ppb range. So lots of frequently changed carbon after the ozone.

[d2mini]

400's here, dips to low 300's during a wc. Dips down some when adding large quantities of food.

Hey d2mini have you ever noticed any negatives when its that low? I'm assuming your tank is fairly stocked ��

nope, tank seems to do ok regardless.
I've run ozone mainly to help clear up the water a little and my controller makes sure it doesn't climb over 400 mV.

[doctorwhoreefer]

Well this makes me wonder :-\
With weekly 15g water changes, my 75 gallon stays between 400 and 420ish?
I don't use ozone.

The reason I ask d2 is because before I took out a porcupine puffer, 2 clowns, and a green wolf eel my orp stayed around 230? Iirc. Stuff looked good but after taking those fish out and now I just have 10-15 frags/colonies, and a lawnmower blenny, orp skyrocketed and stuff looks amazing now.

I put the apex with orp on the system about a week before rehoming the puffer because of size, figured I would regime the others though and setup a minimal-fish tank and get some more small invertebrates and such since I've had puffers since way back. Its a lot more fun now adding stuff to the tank knowing they wont get eaten. :)

Should I be worried about the 400+ orp? I mean really, the corals have never looked better, but if I killing something unknowingly.. Maybe cut back on wc's to every two weeks?

[d2mini]

No, that level is fine.
I just cut it off there because by that point there is no need to add more ozone and make it even higher.

And make sure to clean your probe every couple weeks.
I know with mine, as it starts getting dirty, OPR levels artificially rise.

[wolfblue]

I don't use ozone...
Should I be worried about the 400+ orp?

No you just look for it to suddenly be much lower, or much higher. I don't think many people can be at 400 without ozone. If you were to take a probe out of tank water at 400mV and put it in a good 400mV solution it would probably read 350 or less.

Same for taking it out of the sump at 400 and sticking it in the display tank. The sump probably will be much higher. Without ozone its just a number that you judge against itself. The value doesn't matter, a big change could.

If your using ozone you need to try to get and stay closer to a more accurate number. You can keep using a cheap probe but you have to understand that it probably will start drifting up the day after you clean it. With ozone you need a routine of probe maintenance. After a while if not much has changed in your system you will know what the drift is. You learn the system and how it and the probe will behave.

I am not just parroting what I read on the net someplace. ORP in aquariums is a big part of how I make a living. If I was using ozone at home I would consider a better probe (http://www.coleparmer.com/Category/Electrodes_Laboratory/3527?SortBy=6&Page=1&AppliedFilters=2000002671,4285328768). At work my probes cost about $350, and one ORP setup cost about $3k just to see a number. I choose the equipment here and I set it up. And if I get a dozen blind penguins or wipeout a thousand pounds of rare fish its all me.

[doctorwhoreefer]

I know the feeling, work with thousands of pc's everyday.. :)

I think its the lab grade, whatever came with the gold package.
I also have no sump, so that might account for it a bit?

Any other things to look for with trends? I see it dip at times with wc's and heavy feedings, is there any instances in which it can go up? I know of deaths as well will cause it to tank... (ba dun ching)

[ca1ore]

ORP = Overrated and Really Pointless. Maybe if you run ozone, but I stopped doing that 20 years ago when my Sanders ozonizer died and I got thoroughly sick of baking the dessicating beads in oven. I do still monitor ORP, but never actually know for sure what a reading means versus another and never actually do anything as a result. I think if you are remiss in tank maintenance perhaps it could be useful as an early warning indicator, but if you are good at husbandry, overrated and really pointless.

[Madehtsobi]

My ghl probe says 450-460 and drops under 400 after a small 5 gallon water change... And a few days later it'll go back up..No ozone here either

[HiFidelity]

I can attest to the drifting reading on ORP probes, I cleaned mine last night & it went from 440 to 360 in the same water.

[Raul-7]

It's great monitoring large spikes, that gives you an indication something is wrong like when slief's son poured bleach into his tank - the ORP shot up through the roof.

[slief]

It's great monitoring large spikes, that gives you an indication something is wrong like when slief's son poured bleach into his tank - the ORP shot up through the roof.

Shot up for a brief second and then tanked like a brick for days.. I worry more about the tanking like a brick part as that was the indicator of the crash immediately following the bleach.

I've monitored ORP for 15 or more years now. I use it for trending and early warning. Truth is that it hasn't saved me from any disasters but a subtle change can be an indicator of a casualty or something amiss in the tank. I've followed my ORP trends when switching from one skimmer to another and it's been interesting to see the results as more dissolved o2 can increase ORP just as increased DOC removal can. It is however a number I look at every morning before I go to work and every night before I go to bed just incase something has gone wrong in my water. My ORP remains in the mid 300's so any major change is a sign of trouble. Short of visually looking in the tank, ORP is about the only reading that can tell you anything about your water quality. AS such, I have alarms in my Apex programming to notify me if ORP has a drastic change.