ORP

[DrBegalke]

Is ORP a useful measurment if you aren't running ozone?

My nano tank is running about 150 mV right now, not sure if I should try and increase it... and if so, how?

I have read Randy's article on ORP.

[snorvich]

If you are not running ozone, there is no reason to think about ORP. If you ARE running ozone, it is a way of controlling ozone usage. Just be sure and calibrate probes frequently.

[DrBegalke]

That's what I was thinking as well.
Thought I would get other opinions.

[Randy Holmes-Farley]

ORP might be useful to gauge how successful various husbandry practices are, and might be useful to detect sudden problems (like a dead fish), but I've not noticed such usefulness in my case (although I do run ozone, it is not on a controller).

[DrBegalke]

Thanks for the input Randy.

I'll experiment with it and see if I notice anything.

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.

[Nanook]

Randy,

Do you see any benefits to running ozone?

[Randy Holmes-Farley]

Yes, the water is visibly clearer (less yellow). I skim and use carbon and would have said it was clear before ozone, but it was demonstrably clearer after starting ozone.

[aninjaatemyshoe]

You can use ORP to determine how much flow through a nitrate reactor you should have.

[brward5]

antecodally... i'm noticing the ORP increase in my QT tank as it ages and the biowheel becomes more seasoned. When I first set it up, biowheel was new, water was new and required daily water changes to keep ammonia levels down, ORP rarely broke 200. Several weeks later I'm regularly seeing ORP values over 300 and the water is much more stable. I haven't performed any controlled experiments, this is just my observation.

[erikages]

According to Sprung and Delbeek ("The Reef Aquarium," volume 3, pp326-330), running a small amount of ozone (e.g. 5 mg per hour, if mgs are the right measurement) helps to "align" large org. molecules and thus makes them more available to the skimmer.

Too much (sterilizing quantities) dramatically reduces a skimmer's productivity.

Based on Sprung/Delbeek, I reduced ozone, and noticed a wonderful increase in the quality of skim.

Hope this helps.

[Randy Holmes-Farley]

FWIW, I'm not convinced that they are correct in that regard (a small amount helps individual molecules become more skimmable), but it is certainly clear that ozone can substantially reduce the skimmate formation, even at way below sterilizing doses.

I discuss those issues here:

http://reefkeeping.com/issues/2006-03/rhf/index.php#11

from it:

Oxidation of Organics by Ozone: Skimming and Nutrients


Another result of breaking some organics into smaller, more hydrophilic bits (Figure 3 and 4) is that it often increases their bacterial biodegradability. Therefore, the ozone may need only to start the degradation process, and bacteria in the aquarium can finish off the organics by uptake and metabolism. Large humic acid molecules, for example, are converted by ozonation into smaller fragments that are more readily taken up and metabolized. This process may, in fact, be why some aquarists report drops in nutrient levels after initiating ozone. It is not because ozone directly impacts either nitrate or phosphate (it does not react directly with either), but the newly bioavailable organics may drive bacterial growth, just as adding ethanol (e.g., vodka) or sugar might. The growing bacteria need nitrogen and phosphate, and if they satisfy those needs by taking up nitrate and phosphate, the levels of those nutrients in the water may drop. That effect, however, may be only temporary as the initial burst of new bioavailable organics winds down, and a new stable state is reached with lower levels of organic material and similar levels of inorganic nutrients.

Skimming is a complex process that has many subtleties. The previous sections have discussed how ozonation modifies organic molecules , and we can then extrapolate how those processes impact skimming. Years ago it was widely claimed that ozone use increased skimming, and I claimed then that I didn't see how that could happen directly. Most organic compounds likely to be found in significant quantities in a reef aquarium will become more polar and likely less skimmable after it reacts with ozone. Figure 3, for example, shows how oleic acid (readily skimmed) gets converted into more polar compounds that will not be so readily skimmed as they will not be as strongly attracted to an air water interface.

A small portion of organic molecules in reef aquarium water may become more skimmable if, for example, they become more hydrophobic after reaction with ozone. They may also become more skimmable if they were totally hydrophobic before ozone and were transformed into molecules with polar and nonpolar parts (called amphiphilic) which more readily absorb onto an air water interface and are skimmed out.

Are there other ways that skimming might be increased besides these two processes? I hypothesized in a previous article that it was due to the growth of bacteria (either in the water itself, or bound to surfaces), and possibly also the release of new organic molecules as they grew, that caused the effects some aquarists observed.

It seems as if the tide of opinion has turned, however, and most aquarists now claim that the amount of skimmate is reduced significantly when using ozone. Many claim that the collection of skimmate has nearly stopped in their aquaria when starting ozone. Why the difference compared to past opinion? That's hard to say, and may depend on the types and qualities of the skimmers available now compared to years ago, as well as changes in other husbandry practices. In any case, the overriding experience of many aquarists today is that skimming is reduced, and the presumed reason is that the organics are being made chemically less skimmable by ozone. The remaining organics would then be removed more by bacterial processes than before the initiation of ozone in the same aquarium.

[erikages]

Interesting, Randy. I'm tempted to shut down my ozone for a week and see if it makes a difference.

I'll let you know.

Cheers,

Erik

[Randy Holmes-Farley]

FWIW, I continue ozone despite the recognition that it likely decreases the skimmability of the system to some extent.

[erikages]

Well, I've reduced the "on" mode to anything below 325redox, so I'll see if my skim levels increase at my new base orp of 350 (which doesn't trigger ozone).

But this introduces a too many variables to make an observation, it occurs to me. 1. I have a higher level of ORP that seems to have nothing to do with ozone. 2. the skimmer may respond differently to the higher orp regardless of ozone.

Arg.

[Randy Holmes-Farley]

It certainly won't answer the question whether the book or my theory is correct about the mechanisms involved, but it will tell you whether skimming is improved by reducing ozone.

[ReefWreak]

In my limited experience of monitoring my ORP, my 120g thriving SPS tank barely hovers above 200, if even, often hovering around 180mV. I do not dose ozone, but monitor ORP to look for tank changes since I've got a web accessible aquarium controller, and am away from my tank for very long lengths of time (3-7 weeks at a time). I feel that while my family are watching the tank, they frequently don't notice little changes, and little changes are never without consequence in a reef tank. I feel that ORP is just a back-up monitoring system.

[erikages]

200 is basically where my tank hovered, too, before ozone. The ZEObak additive has increased this to t stable range of 350 to 375, it seems. Thus far, it's stable.

I treat ORP the same, btw. And with a Profilux wlan system, I can and do access the tank from a distance, as it gets left in the capable (?) hands of the alarm monitoring company when I'm away! If the orp alarm goes off (which I've set to trigger if the orp varies by 50 points in either direction), I can look at other parameters on line and make a call to one of my "fish friends" if I'm away. I have to say: thank the dear lord for auto top off, which has enabled one to two-week trips away from home without having to hire fish baby sitters.

The alarm company responds if the flood sensor in the fish room is triggered -- which is their own sensor that links into their monitoring system. Handily, instead of having one of their security guards come out (if I can't be reached), one of my fish buddies is on their call list. I just couldn't imagine a security guard looking into my fish room and having the faintest idea what to do. It looks like something the borg would've built to take a pee or something equally waterbased but subsequently burdened with gadgetry.

Erik

[speeddemonlsr]

Is there any good articles on how to setup an ozone to work with your skimmer, if that the best way? I have been reading the articles about it, but havent seen any pics.

[erikages]

There are lots of writings on this, yes! Opinions differ, but there's a general consensus that if you're going to employ ozone, it's best to have the ozonated air go directly into the aerated updraft of your skim. My own skimmer (Aqua C EV-120) came equipped with an ozone input, and many do provide this as an option.

The other direction is to employ a separate ozone reactor in your system and leave your skimmer alone.

In either case, you will require a filter for the skimmer or reactor air output, as you don't want un-carbon-scrubbed ozone going into your house! Too, ozone can influence the nastiness of the smell of your skimmer (this hasn't happened to mine), and your home can end of smelling like something died. Thus the use of a carbon filter for outoing air.

Hope this helps. You'll find that there's a huge amount of differing opinion on where and how to employ ozone in your system, but the two alternatives above are the two most common solutions.

[Randy Holmes-Farley]

Is there any good articles on how to setup an ozone to work with your skimmer, if that the best way? I have been reading the articles about it, but havent seen any pics.

I don't think that is the best way, but some folks do it. I discuss options and show some pictures here:

Ozone and the Reef Aquarium, Part 2: Equipment and Safety
http://reefkeeping.com/issues/2006-04/rhf/index.php

[erikages]

Great article, Randy. I'm tempted to use a reactor instead of a skimmer.

For the fellow who's just starting, do read Randy's article -- and he's right, most folks do run ozone through their skimmer, as I do.

Here's a few points from a fellow who runs ozone through a skimmer:

1. I run minimal ozone (e.g. 5mg) through a skimmer that's ozone safe (good plastics) and has a high water volume in its foot.

2. The air is passed through a drying chamber before the ozone box, then passes through GAC after leaving the skimmer. Thus, I don't smell any ozone in the fish room (I certainly do if I open the skimmer cup!).

3. The water exiting the skimmer is passed through a stand-alone GAC canister before reentering the sump.

4. The ozone box and air dryer is on a shelf above any water levels to prevent the inevitable flow back which would damage the equipment.

5. I use low levels of ozone, in conjunction with an orp monitor and switch, due to my readings on the benefits to skim. Increasing ozone to higher levels (e.g. 50mg) does, indeed, impact skim--in fact it can stop skimming altogether!

Nevertheless, if you've got the sump/fishroom space, the time and the money (aside from DIY time, which can save money), a separate reaction chamber seems to be the best way to go. I'll be doing this myself when I've the time to organize it.

Hope you're not overwhelmed, and thanks to Randy for his careful work in this controversial area of reef-keeping!

Erik