Does UV cause ORP to spike?

[Saltees]

So whatever happened? Did it just end up not correlating? What was causing the ORP spike?

Inconclusive. My bad though, my earlier results were incorrect, cos the ORP probe was plugged into the PH port instead, therefore ORP constantly hovered between 100-200, despite UV and/or OZONE. Now my ORP fluctuates between 400-450 inversely to what my PH indicates, and only on UV.

 

[Randy Holmes-Farley Verified Community Expert]

Now my ORP fluctuates between 400-450 inversely to what my PH indicates.

That's normal and expected. :)

 

[Reef'in Rob]

I know this is an older thread but some googling led me here Here is my experience over the past few days. I had some issues with algae growth so I switched my UV to "On" in fusion I stead of the scheduled program. The next morning my ORP had plummeted down near 50 from the mid 100's. Thinking it was die off related I didn't corelate it directly to the water itself but the organics within the water if you can separate those two in your mind for a second. This evening I decided to give the UV bulb a rest after 48 hours of continuous operation and then to my astonishment my ORP Alarm turned off and shot back up to just over 100 within 20 minutes. I plan on doing some more experimenting with this but there was undoubtedly a direct correlation and near instantaneous effect on a RS 425 G2+ sized tank which kind of took me by surprise even with 20 years or so in this hobby. Always learning something

 

[Tangdora]

Will chime in on this simply because I upgraded my uv from 57w to 228w on my 360 gallon this past week. While I have notice several improvement so far, the bump up in UV wattage did not affect my orp in any way. Though I was already running in the 400s prior to adding. The affect is probably more noticeable when adding one at lower orp levels.

Added on 9/8. Here is the before and after i upgraded.