ORP

[Chris_W]

Do any of you measure ORP in your reefs? I picked up a controller that has an ORP probe, and will be wetting it up soon, but can't really wrap my head around what ORP signifies in a reef. I've read RHF's reefkeeping.com article on the topic, and understand the premise, but am still far from understanding it's application.

If you measure ORP, what do you use the measurement for? Does it signal you to do a water change, that an animal has died, that something is wrong with your tank? I think some real-world applications will help me understand this better.

Thanks!
- Chris

 

[TheRealChrisBrown]

Following along, just for educational sake. Good luck Chris, hope somebody can help you out!

 

[Chris_W]

Thanks man, hope so too. Would prefer to get some valuable info out of the piece of equipment.

I did a little more research and found people referencing it as a tool to trigger them to perform a water chance. Still digging to find out if there's any merit to that line of thought.

 

[Munch]

Good read:

http://reefkeeping.com/issues/2003-12/rhf/feature/

 

[SynDen]

It is a hard number to wrap your head around but I look at it like one more possible early warning monitors in the tank. Really all you are watching for is drastic changes in it. If you suddenly saw it swing up or down you would have some indication that something wasnt right in the tank. Things that I can think of that can influence orp reading would be, equipment failure like with a calc reactor, or doser getting stuck on, large algae blooms, chemicals like chemiclean, or anything that would add or remove dissolved oxygen from the water column. Any of these things could result in a full tank crash if not managed correctly, so it can just help aid in the prevention of that. Its no magic wand or anything, but just another possible tool that you can use to "hopefully" prevent a crash

 

[Chris_W]

I found this resource as well,

http://www.reef2reef.com/blog/orp-potentially-the-most-influencial-parameter/

 

[zombie]

Are you measuring continuously with alerts (like an apex or reef keeper)? If not, there is no point in measuring orp. Basically with orp, you are looking for trends. If the value raises or lowers sharply beyond the normal daily range, than it can be a quick indication that a fish might have died, an auto feeder dumped in too much food, skimmer is overflowing, etc. If you manually measure orp, these changes will settle out in no more than an hour naturally (unless your tank is crashing) and really doesn't buy you anything.

 

[Chris_W]

yeah, it will be through Apex. The system is still in a box, was just looking at it yesterday and realized that I had no idea what the readings meant.

 

[zombie]

If that's the case, then let the probe soak in your sump for a week and disregard whatever reading it says during that time. Over the second week, get an idea of what you high and low limits are for the week. If for example it ranged from 300 to 325, then add the following lines to your email alarm.

If orp < 270 Then ON
If orp > 355 Then ON


If either of those send you an alert, then check on you tank as soon as you can to make sure nothing died and the skimmer is working right. You can adjust those if you get nuisance alarms or the typical range shifts, but usually 30 outside normal values does the trick.

 

[Chris_W]

Thanks. So out of range ORP in your case signifies the death of an inhabitant or decreased efficiency in your skimmer. Do the readings on yours tend to drop toward the lower range over time as well? There was a long thread in another location where someone was using ORP readings as an indicator to perform a water change.

Sorry if these questions seem a big ignorant, i haven't had a chance to review any historical data yet.

 

[zombie]

Orp can drop over time between water changes, but it isn't a great indicator for timing water changes. In a well balanced system with good skimming and plenty of live rock, the normal range should not drop much over the course of a week (most I have seen see less than 10 mV drop between water changes). However, if you do notice the range dropping a lot between water changes (remember that orp is inversely proportional to pH, so a 25-50 daily fluctuation is to be expected. Compare values to the same pH at similar times), then it can indicate that your skimmer isn't efficient enough as is to keep up with your current bioload and you need to skim a little more wet and/or do larger water changes each week.

 

[Chris_W]

Awesome, thanks again for the info. Hopefully I'll be able to get the system set-up this weekend and start capturing info.