Activated carbon leaching iron?

[MoparMike97]

Hey guys,

While doing some maintenance today, I noticed discoloration on a bag of carbon I added a few days ago. Initially I figured it was just some bacterial/algal growth but after pulling it out, I'm almost certain it's iron/rust staining.

This bag was added to the tank about 5 days ago. It's a nylon mesh bag filled with Marineland Black Diamond activated carbon, which I've used many times and never had any issues.

I'm not ruling out external contamination either, this bag was placed right before the return chamber in my sump, so it would likely catch any debris from other equipment in the sump or in the tank. Going to start checking pumps, magnets etc. and see if there's anything suspect.

Anyone else ever had carbon do something like this? And is there media available to absorb iron out of the water column?

Thanks.

 

[Randy Holmes-Farley Verified Community Expert]

I don’t believe the GAC itself released iron, and it is very unlikely iron is high enough to be a concern. Some people dose it very high.

I’m not sure what that is, however, or how it got there.

 

[Sophie"s mom]

Hey guys,

While doing some maintenance today, I noticed discoloration on a bag of carbon I added a few days ago. Initially I figured it was just some bacterial/algal growth but after pulling it out, I'm almost certain it's iron/rust staining.

This bag was added to the tank about 5 days ago. It's a nylon mesh bag filled with Marineland Black Diamond activated carbon, which I've used many times and never had any issues.

I'm not ruling out external contamination either, this bag was placed right before the return chamber in my sump, so it would likely catch any debris from other equipment in the sump or in the tank. Going to start checking pumps, magnets etc. and see if there's anything suspect.

Anyone else ever had carbon do something like this? And is there media available to absorb iron out of the water column?

Thanks.

I also use Marineland Diamond carbon, and when I change it in my filter, I periodically see small rust stains in. I don't sweat it.

 

[MoparMike97]

Thanks! Glad it's nothing abnormal. The was the first time I've run it in a bag, I had previously been running it in a media reactor so I probably just never noticed the staining before. Appreciate the help!

 

[Randy Holmes-Farley Verified Community Expert]

Id caution on the interpretation of where the colored material comes from and what it may be.

Precipitation of calcium carbonate from my kalkwasser was totally white, but after exposure to my tank water, discolored to look like the picture above.

What is that Precipitate in My Reef Aquarium? by Randy Holmes-Farley - Reefkeeping.com

Figure 4. When limewater drips onto surfaces, such as the sides of a sump, precipitation of calcium carbonate takes place. The off-white coloration probably comes from metals such as iron binding to the calcium carbonate surface in the place of calcium.​

 

[Devisissy]

My ro carbon block does this. My reactor does this. I never did sort it out. We are on a natural aquifer that filters the water via lime rock. So I'll take Randy's explanation.

 

[sayurasem]

My carbon does the same. I’m using red sea carbon.

 

[Randy Holmes-Farley Verified Community Expert]

I'd just ignore these color issues. I do not consider it a sign of a problem.