Can someone explain ORP to me???

[SomethingFishy]

om I bought an American Marine ORP meter. It did not come with calibration fluid (it's coming in from the store) However, in the American Marine instructions it says that you do not need to calibrate so I am a little confused there.

Anyway all that a side I get a reading of 285 on my Predator FOWLR tank. From what I have read ORP meters are like an overall guage of knowing the system stablity. Is there some sort of guide line as to where and when the panic affect should kick in. Like uh oh it's 200 time to clean it or something?? Do you need to calibrate these monitors or am I missing something.

SomethingFishy here.......

 

[Trogdor]

http://www.marineandreef.com/shoppro/electronics_pinpoint_orp_instruct.htm

That link gives the guidelines on where the 'OH S***' range should be.