Can this be right ? High ORP

[MaLi]

Greetings,

About two months ago I purchased an ORP meter (Pinpoint) and I started monitoring my tank. I have calibrated the meter once using the provided 400 mV solution and bought and checked other two times with similar solution. No problems with the meter at all. After calibration it was holding 400 mV whenever I re-checked.
But, the meter reads around 375 right at the end of MH light time (6:00 PM) and drops to around 325 in the morning before the lights are coming on. Can this be right ?? After so many checks with the standard solution I don't think the meter is bad, but these values for the ORP are reported by people using ozone and I don't. Randy reported that without ozone his tank is on lower 200s ?!?

cheers,
Marian

[bertoni]

I wouldn't worry very much. A good skimmer can do a lot to maintain high ORP, and maybe your feeding rate is lower than many others, for example.

[Boomer]

Marian

You can get those levels in a well run reed tank, it is quite common. Over 400mV without Ozone is another issue. The sifts you are seeing are normal. So, as Jon stated don't worry about it.

[MaLi]

Thank you guys. Appreciate and value your opinions.
I have an external skimmer a Turboflotor Multi run by a mesh modified Aquabee 2000 pump. The pump really pushes the skimmer at the high end extreme. The whole body is a net of bubbles.
I was thinking about ozone, but I don't think I need it at this time in spite of being heavy stocked. I feed mostly a variety of frozen food.

cheers,
Marian

Boomer; just out of curiosity - what can drive the ORP value over 400 mV without ozone ?