The above quote is taken for the article I linked in my prior post. It seems it is important to watch the trends in your tank.ORP measurements are very susceptible to errors. Aquarists are strongly cautioned to not overemphasize absolute ORP readings, especially if they have not recently calibrated their ORP probe. Rather, the most useful ways of using ORP involve looking at changes in measured ORP.
I believe that ORP is a very beneficial measurement if you are using ozone. I do not use an ORP monitor, as I don't use ozone and also, I agree with Mike when he said the following:It sound as if you bielieve that ORP is a useless measurement? Do you use a orp meter?
Anyway you could loosely relate it to water quality, but usually you will have a lot of other signs in the tank to let you know things are not going well.