ORP Questions

[swarf]

I'm just talking off the top of my head..., but isn't there something about keeping your different probes a certain distance from each other so that they do not "interact" and give erroneous readings?

 

[jmaneyapanda]

Swarf;36015 wrote: I'm just talking off the top of my head..., but isn't there something about keeping your different probes a certain distance from each other so that they do not "interact" and give erroneous readings?

Ive never heard of that- some sumps have probe holders which are about an inch apart.

Mwitten is also correct, a lot of factor can influence the ORP, including pH, temp, and duration in water. But anyway, I know for a fact (from the manufacturer) that the probes have a limitedly useful life, andf do need operiodic replacement (Pinky at Red Sea told me every six months!).

 

[siege]

Thansk for the explanation of ORP, that was exactly what I needed/wanted to know!

 

[swarf]

jmaneyapanda;36019 wrote: Ive never heard of that- some sumps have probe holders which are about an inch apart.

Yeah, I've seen probe holders with very close spacing as well...and really haven't heard of anyone claiming it caused a problem. But there you have it, I have no idea what would cause interaction or interference. I'm not trying to be a pedant, just trying to prove to myself I had seen at least one reference, and wasn't just imagining it.

Here is one reference from American Marine, who makes Pinpoint monitors, which states minimum 3 - 4" spacing.

http://www.americanmarineusa.com/orpmonitor.html">http://www.americanmarineusa.com/orpmonitor.html</a>

I'm not positive, but almost sure I saw a recommendation for even greater spacing somewhere, like 6 or 7 inches.

Chuck

 

[mojo]

Sorry I'm so late on coming in on this. I'll be brief-

I have some ORP calibration fluid if you'd like to borrow it.

An ORP of 75 would mean your tank would be dead. Something's up with your probe.

I have a ISE meter (generic meter for measuring all types of high-impedance probes, including ORP), if you want to check out your probe itself.

Lastly, yes, you can get interferrence between probes in the same body of water. It's related to the reference electrode used by the pH probes and the method by which most ISE probes work. Remember that they create a voltage potential across the elements, which mean they're highly sensitive to stray electrons. High end probe setups will use a separate reference probe and place the ISE probes equidistant from it. For our cases, just move them around until you find what works.