300w heaters produce dramatic increase in ORP

[madweazl]

For the past few weeks, ORP has been averaging about 235. Today, I replaced the 3, Ehiem Jager heaters I was running (200w each) with 2, BRS titanium heaters (300w each). ORP instantly jumped to about 335. Unplug the heaters and ORP instantly drops back to 235. Install either heater and it goes back up (one or both heaters provide the same ORP value). I checked for stray voltage and have 0v measured without the heaters installed and 0v with the heaters installed (again, one or both heaters provide the same value). I get 2.5v from neutral to water (relay on the GHL that isn't on). Nothing is on a GFCI. Everthing is plugged into a grounded 3 prong outlet. The only submerged, powered device in the setup is my skimmer (besides the heaters). No measurable stray voltage with just the skimmer running. ORP value doesn't change if the skimmer is plugged in or not.

Any ideas on what causes the change?

Same post is in the GHL forum here.

 

[Amado]

I have always been under the impression that the higher the orp the better.
I usually run my tank from350-400
I do a water change when it drops under 300

 

[madweazl]

I have always been under the impression that the higher the orp the better.
I usually run my tank from350-400
I do a water change when it drops under 300

The value doesn't concern me. I'm after the root cause of the delta.

 

[minus9]

It just could be RF interference from the electronics of the heaters in relation to the ORP probe?

 

[C. Eymann]

How close is the ORP probe to the heater elements? how close are the heater power cords to the ORP cable? possibly interference.

 

[madweazl]

Heaters are in the skimmer chamber (four inches from the probes but the bubble trap is between them). Probe wires run up over everything but there is six inches between the wires at the closest point (where they enter the sump). The ORP is high with the heaters just being installed (not operating). There is no difference in the readings if the heaters are on or off.

Original heaters were in the second chamber but now they're in the same location, one chamber to the right with the skimmer.

 

[User1]

Interesting. I probably would have asked the same question as well if the only change was swapping heaters. Especially if I replaced them and it went back to what it was. That would have ruled out me saying maybe I knocked the probe and got a bubble causing the issue. Interference sounds plausible. If you haven't you could try and isolate the cords to the best of your ability and see if that changes anything.

I wouldn't expect the change in ORP after the swap though. Really odd.

 

[minus9]

It could be the difference of materials? Glass vs titanium?

 

[dragon99]

With the titanium heaters in the water but unplugged does the ORP change? You checked for stray voltage, but that still seems like the obvious candidate.

 

[Macdaddynick1]

Nvm saw the reply

 

[madweazl]

With the titanium heaters in the water but unplugged does the ORP change? You checked for stray voltage, but that still seems like the obvious candidate.

Unplugged it drops back down to the original range. Plugged in, operational or not, it jumps back up. This happens with either heater plugged in or both so not isolated to one heater.

 

[dragon99]

Definitely related to the fact that the titanium heater is providing a ground then. Past that observation I'm out of my depth to explain why if there's no measurable voltage. My guess is that it's very slight, not enough to register on a meter, and the ORP probe is more sensitive.

 

[User1]

Not sure if you have done this yet but shoot BRS a email and let them know. I actually have 2 x 300 watt heaters but I'm not able to hook them up yet otherwise I'd test. I have 1 500 watt titanium heater (Finnex) currently so would be interesting to see if I'm seeing what you are.

 

[ingchr1]

Do you run a ground probe?

If not, is there a way you can ground the water with the heaters out to see if the ORP probe exhibits the same response?

I'm thinking it has to do with grounding the water.

At an outlet by the tank what do you measure between ground and neutral? Is it also 2.5V?

 

[madweazl]

Do you run a ground probe?

If not, is there a way you can ground the water with the heaters out to see if the ORP probe exhibits the same response?

I'm thinking it has to do with grounding the water.

At an outlet by the tank what do you measure between ground and neutral? Is it also 2.5V?

I don't run a ground probe on the tank. Had one but I think it was given away.

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.

Back to your other thread to see why this is having such an effect on your ORP probe.