Interesting ORP observation with different carbons

[BriDroid]

I’m not sure if I am really seeing something, or it’s just a coincidence? I usually run BRS Rox 0.8 carbon in my BRS mini reactor. My ORP usually sits around 300-330. This week I decided to use some Red Sea Reef Spec Carbon. Within 8 hours or so my ORP started rising and is now sitting around 350-370. I don’t use ozone either. What’s funny is that the Red Sea stuff doesn’t seem to remove as much smell as the Rox 0.8. It’s not horrible, but I can definitely smell the ocean in my office where I never have before. The water is still crystal clear, just has that ocean smell.

 

[jabberkaycee]

Do you have any of the Rox left? Once the Red Sea carbon is depleted, it will be interesting to see if the numbers drop back down if you switch back to Rox.

 

[Randy Holmes-Farley Verified Community Expert]

ORP is a very complicated thing to interpret. It is generally reporting the relative ratios of different trace metals, such as the ferric vs ferrous iron forms.

GAC will bind organics, ,and some GAC types may bind or release trace elements directly. Many trace elements are bound to organics, and the different metal forms will bind differently.

Thus, I think it is difficult to pin down a mechanistic reason for GAC brands to have different effects on ORP.

 

[BriDroid]

Do you have any of the Rox left? Once the Red Sea carbon is depleted, it will be interesting to see if the numbers drop back down if you switch back to Rox.

I have both. This last time I mixed half Reef Spec and half Rox. Three tablespoons Reef Spec on the bottom and 2 tablespoons of Rox on the top. I already have to use 3 sponges to keep the carbon from moving/channeling anyway, so separating them was no big deal.

My ORP is running around 375 with this setup after a week. My plan is to try and run it 2 to 3 weeks and see if the ORP dropping signals that it’s time to change it.

One thing with this combo, the ORP is high and the “ocean” smell is gone. The water is crystal clear. I just might have found something that works for this tank.

 

[jabberkaycee]

I’m going to follow this thread so I can see how it plays out. I just bought the BRS mini reactor today and plan to use 3 parts Rox to 1 part GFO. That will fill the canister and I will get the clarity, with some phosphate removal, and not have to worry about tumbling. I watched a BRS video that recommended doing that.