Reef Chemistry Question of the Day #194 Low ORP in New Salt Water

[Randy Holmes-Farley]

Reef Chemistry Question of the Day [HASHTAG]#194[/HASHTAG]

New salt water used for a water change sometimes lowers ORP. Which of the following ions that might be in the new water CANNOT POSSIBLY be an explanation for the ORP reduction?

1. Ferrous iron (Fe++)
2. Ferric iron (Fe+++)
3. Iodide (I-)
4. Iodate (IO3-)
5. Cupric copper (Cu++)
6. Cuprous copper (Cu+)

Pick all that you think might apply.

Good luck!

























.

 

[Randy Holmes-Farley]

Sorry, this one may be a bit too hard...

 

[Kershaw]

I'll take a guess and go with 3

 

[twilliard]

This one is tough for sure!
I have to split between 3 and 4

By the way did you know h2o2 drops orp?

 

[Randy Holmes-Farley]

This one is tough for sure!
I have to split between 3 and 4

By the way did you know h2o2 drops orp?

Nope, not other than some hypotheses. Do you?

A little testing might clarify whether it is a direct effect of H2O2 (and included stabilizers, if any) in seawater, or only once it breaks cell membranes open, but at this point I do not know even that much.

 

[Cory]

Ill guess 1,2,5 and 6. Just a guess though.

 

[beaslbob]

all of them.

 

[twilliard]

Nope, not other than some hypotheses. Do you?

A little testing might clarify whether it is a direct effect of H2O2 (and included stabilizers, if any) in seawater, or only once it breaks cell membranes open, but at this point I do not know even that much.

Just basing off of people Apex orp readings which stumps me
Thank you randy as always for your input!
(Sorry if this is off topic!)

 

[ElectricMusic]

I would guess 5 and 6 (copper?)...

At any rate, is there a way to prevent this from happening? It takes a day for the ORP to get back to normal...

 

[Randy Holmes-Farley]

And the answer is...2. Ferric iron (Fe+++), 4. Iodate (IO3-), 5. Cupric copper (Cu++)

I know this one was very hard. The main point of it is to remind folks why new salt water has a low ORP, and that it is not a sign of anything bad in the water.

The answers are all the most oxidized forms of these species usually in the water, so those cannot lower ORP.
The other three answers are the more reduced forms, and those three all could lower ORP if present in the new water.