ORP Scaring Me

[Jaws]

Let me give you some background info first:

I've got a Neptune Aquacontroller III that I use to run a PinPoing ORP probe, which came with the controller. I've got an X10 module hooked up to a Red Sea 200mg/h ozonizer which I have set on 25%. I have the controller set so if ORP is greater than 300 then the Ozonizer shuts off and if the ORP is less than 250 then the ozonizer turns on. I should also mention that the ozonizer is hooked up to an ozone reactor rather than pushing it through my skimmer. I did this to help prolong the life of the skimmer. I have water from the return chamber of my sump being pushed into the ozone reactor using a maxijet 1200. Once the water passes through the ozone reactor it goes through a Fluval 404, which I have dialed down to slow the flow. The 404 is full of carbon to help detoxify any leftover ozone which returns to the first chamber (overflow) of my sump so hopefully any leftover ozone gets eaten up by my skimmer. There's also a Carbon filter pad in between the final baffles before the water reaches the return chamber.

My problem is that once the controller tells the ozonizer to turn on, the ORP starts to climb slowly. Once the ORP hits 300 the ozonizer shuts off but the ORP continues to climb to over 400. It was 430 when I left this morning and still slowly climbing. I'm praying there's something not reading correctly and I'm not going to come home to a crystal clear but completely dead tank. Even before the ozonizer was hooked up the ORP would vary daily anywhere between 220 to 350 without any other influence. Anyone have any suggestions on why this is happening?

[TheReefGeek]

Where is your ORP probe located? Only thing I can think of is that your ozonizer is pumping in ozone into your tank, but the ORP is "spread around" the rest of your tank until quite a while, so by the time your ORP probe detects the increased ORP, the area your ozone is getting injected into is much higher than your desired level, and when this "spreads out" to your probe, you have a much higher ORP than desired when the unit kicks out.

If this makes any sense, then you could try relocating your ORP probe closer to the output of your canister filter lets say, and you might not get as big of swings.

Also, if you know someone else with an ORP meter, borrow their unit to verify the readings against yours, maybe your controller/probe is wonky.

[BMW Rider]

There is a series of articles in the last three months in Reefkeeping Magazine (http://reefkeeping.com/index.htm) on ReefCentral that might help you with some answers. I kind of glossed through them, since I don't have ozone on my tank. I recall that the reaction time of the meters was discussed in one of the articles.

[Chin_Lee]

Jason
clean the probe with a toothbrush. If i don't clean mine, it climbs and climbs and climbs. I have to clean mine every 2-3 days to keep the readings accurate.