ORP of 245?

[lactose]

Hello all-

I got a new ORP meter and probe on Thursday and the probe (pinpoint) came dry (the little plastic jar and sponge on the end were bone dry). The consensus from checking around is if the probe is the type with the little metal pin (which it is) then is should be fine and in fact other brands are shipped dry.

I am trying to decide if it is not good and therefore return it or if my tank really has an ORP of 245?

I calibrated it Thursday night and it was way high (435 or so) so I turned the screw to get it to read 400.

In my tank Thursday night it first read like 120ish.

24 hours later (friday night) it read 177ish.

36 hours - 48 hours later (till saturday night) it read 220-230.

I took it out last night to recalibrate it as a test and it was way low (370ish) so I turned the screw back to get it to 400 (felt like perhaps I was undoing the calibration I did on Thursday...)

When I put it back in the tank it quickly went from 160ish to 210ish in a half hour and is sitting around 230-245 all day today.

My question is: Can I really have an ORP of 245 (seems low to me - and all my inhabitants are happy) or is it a bad probe and the pinpoint ones do indeed need to be not dry?

Params: 35ppt Salinity, 7.5 dKH Alk, ph 8.2 (8.1 - 8.3 during average day), Calcium is 460 (I know I am out of balance/low on Alk and working on bringing up Alk slowly), Mag is 1290. And other than I am fighting down some algae the tank is all happy and growing, eating, extending polyps etc.

I have some pretty decent confidence in the tests because I have recalibrated, bought new and compared multiple test kits from different vendors to get at most of those numbers (due to the coincidence that I was trying to prove it was my "error" that was showing low numbers out of a just opened RC bucket until I saw the threads on here - none of that bucket or any bucket that is low has entered my system).

Thanks

[reef_doug]

From my experience, it could take one week before the ORP probe stabalizes. Especially for a new one.

[bertoni]

I agree. I'd wait a while before worrying. This article discusses ORP:

http://www.reefkeeping.com/issues/20...ture/index.php

[Sk8r]

THank you, Bertoni. I think even understand the front end of that piece. I've wondered about that. You used to hear a lot about it, and hardly ever do now.

[lactose]

Thanks. I had heard hours, 24-36 hours, and a day or two but I will certainly hold for a week and see.

[Boomer]

Yup, a week to be sure all is well.

[Randy Holmes-Farley]

Without ozone, my ORP would run in the 200's. With it, it ends up around 300 mV.