ORP drop with water change

[TWYOUNG]

Without making it extremely complicated, can anyone explain the sudden temporary ORP drop when fresh sw is added to the tank during a water change? Seems like fresh water would be cleaner than old tank water. I do remember very low ORP readings when my tank was first set up.

 

[Randy Holmes-Farley Verified Community Expert]

Sure, new salt mix has low ORP.

The mistake is thinking high ORP means cleaner water. It does not.


Salt mixes are optimized for solubility. Some redoxp active trace elements, such as iron, are more soluble in their low ORP, ferrous form.

 

[TWYOUNG]

Sure, new salt mix has low ORP.

The mistake is thinking high ORP means cleaner water. It does not.


Salt mixes are optimized for solubility. Some redoxp active trace elements, such as iron, are more soluble in their low ORP, ferrous form.

I guess I need to read some threads on ORP again bc it's not easy to comprehend. If I have a big decomposing Turbo snail hiding in my rockscape ORP will likely decline will it not?

 

[Randy Holmes-Farley Verified Community Expert]

I guess I need to read some threads on ORP again bc it's not easy to comprehend. If I have a big decomposing Turbo snail hiding in my rockscape ORP will likely decline will it not?

That dead snail will likely lower ORP, yes.

This has more:

ORP and the Reef Aquarium - Reefkeeping.com