Quick ORP Increase (What to look for?)

[Aaron Atkinson]

Hello and thank you in advance. I have a 50 gallon tank with a refuguium. I monitor ORP using the Apex fusion, as such, I tend to see slow growth in the value between water changes. Water changes tend to rapidly reduce the ORP, as does something dead.

Today I saw a significant increase in ORP: from 304 to 346 over the course of about 5 hours. A very unusual situion. This is remarkable to me as I changed nothing in the system. I did add some soda ash and calcium solution last night, but nothing out of the ordinary.

Is there anything to be concerned about or look for?

 

[Randy Holmes-Farley]

ORP never rises high enough to be concerned if you are not adding oxidizers such as ozone.

I'm not sure why yours rose, but a decline in pH will cause an ORP rise. Did pH change?

Algae growing on the probe can also make ORP rise.

 

[Aaron Atkinson]

Hello Randy. You are a true gentlemen, thanks for the quick reply. It turns out my return pump stopped pumping this morning shortly after I left for work.

The timing I suppose is based on when the ORP value began its upward climb together with temperature. The skimmer cup was basically full of water. So my theory is the skimmer was just running all day, oxygenating the sump water really well. The temp stayed within limits but being in the enclosed sump area remained at an elevated level.

This is the second sicce pump to stop on me without warning. The propeller spins OK by hand, no visible build up, etc. A quick soak in vinegar has gotten things going again.

Gotta be a tough sea critter to make it in this tank.