The why, oh why, 38 stair, 290 gal build revised

[reefwithareefer]

Originally Posted by Roskoreef

what is your ORP normally, i only ask because im wondering if my probe is off, mine is unsually around 440 and drops whenever i muck up the tank or dose certain stuffs, but always makes its way back up.. although my tank is new..

My ORP was usually hovering around 270 and hit a high 300 and a low of 250. ORP will fluctuate depending on numerous things. Feeding, what you are dosing, stirring the substrate etc can all cause ORP to go up and down.

You apparently should clean your ORP probe at least once a month in a vinegar bath. It could take a day for the cleaned probe to read properly again.
From what I have read, an ORP of 440 is pretty high and bordering on causing issues for your tank. My understanding is 375 to 400 is a good ORP reading

These articles really helped me understand what ORP/ozone is/does and what causes it to fluctuate, even though scientists do not fully understand ORP either.

It is dry and technical reading, took me reading it 5 times before it begun to sink in, but the links may clear some things up for you.

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

http://reefkeeping.com/issues/2006-03/rhf/index.php