Some good info:
ORP and the Reef Aquarium - Randy Holmes-Farley
http://reefkeeping.com/issues/2003-1...ture/index.php

for ppl that like to read:

http://reefkeeping.com/issues/2003-1...ture/index.php

ppl use ozone to increase it typically :)

I think you could argue most of the same points for a PH probe. It's not hard to find an expert that claims 'ph isn't as important as we make it out to be'. The general consensus seems to be that stability is more important than a precise value.

I monitor both PH and ORP, but I rarely check either. I've concluded a long time ago that I don't trust the calibration of my probes enough to act on the readings.

I once tried to control PH by attaching a kalkwasser stirrer to a PH probe. I had one near miss that spiked my PH to well over 9 (thank god for vinegar). After tinkering with it for about a year I shut it down and concluded 'it's just not worth it'.

What ORP and PH both do is give you insights into the patterns and swings in your tank. It is actually interesting to see the PH and ORP swings throughout the day. It is interesting to note the effect of water changes on both values. It may not give you an objective measure on the health of the tank, but it will generally tell you if it is running a stable baseline.

I also once had a hydrogen sulfide incident. I didn't need the ORP probe to tell me there was a problem, but it was interesting to see the ORP drop to zero. It was also interesting to watch it slowly climb back up as I took emergency measures.

- Brad

Watching the orp climb after the h2s incedents is a nice feature. I know adding peroxide will oxidize the h2s but without the orp meter it's harder to tell if it was working or if enough 02 was added to system to nutralize it.