Sudden, dramatic, ORP change

[Member No 1]

Thank you. What’s the ideal ORP for reef tank?

I keep mine in the 380-420mV range.

 

[madweazl]

Some additional info from the other thread:

I just double checked to make sure I was providing the right info and I'm not; Neutral was actually Hot. Neutral to Hot is 119v. Neutral to Ground is 1.2v. Hot to Ground is 120.6v. Neutral to Water is 1.3v. Hot to Water is 120.6v. Ground to Water is 0v.

Edit: used some wire to create a jumper from Ground to Water with the heaters unplugged and it provides the same reading as when the heaters are plugged in.

 

[ingchr1]

So it looks like the heaters are not the cause. The voltage you are measuring from water to neutral is from your homes electrical system. The heater is connecting ground to your water.

Why this is having such an effect on your ORP probe I'm not sure.

 

[Andy-D]

Perhaps your ground is not at 0v and there is a small voltage present. By grounding the tank this raises the tank by a few mV. If the case I doubt its measurable as any home test gear would not have a high enough impedance, so try and measure it and it shows 0 volts. it may be worth placing the probe in a glass of tank water and then ground this to see if its tank related of purely your ground ref.

 

[ingchr1]

I just tried to test this on my tank, but when I remove my ground probe I still get 1.2V from water to neutral (what I also have at the outlet). Not sure what's creating the ground path. Could be my AC return pumps, my heaters are glass. When I have time maybe something I can look into further.

What you are seeing may not be an issue at all. With the ground path is it a real rise in ORP?

If you don't get an answer here I would try the chemistry section of the forum.