How often do you change Granular Activated Carbon (GAC)?

[hsp]

I'm wondering how long activated carbon will last. There are different instructions out there for various products and in many posts about the topic, some even claiming "can create some problems if left more than about 60 days". I use Coral Essentials Activated Carbon in a media bag put into the Media Basket of my ReefMat 500.

 

[UMALUM]

I always use 1/2 the recommended amount of spec or rox and change it every couple weeks.

 

[Randy Holmes-Farley Verified Community Expert]

I changed half of mine roughly every 2 weeks or so.

 

[kevgib67]

Every 8 weeks, here but rethinking it based on the above comments.

 

[Pod_01]

I changed half of mine roughly every 2 weeks or so.

So out of curiosity, why 1/2 every 2 weeks?

I change all every 4 weeks, no particular reason. It was stated on one of the brands I used…

 

[Dan_P]

I'm wondering how long activated carbon will last. There are different instructions out there for various products and in many posts about the topic, some even claiming "can create some problems if left more than about 60 days". I use Coral Essentials Activated Carbon in a media bag put into the Media Basket of my ReefMat 500.

If the GAC is present to adsorb color or dissolved organic carbon, it will likely do its job for months.

 

[mjszos]

I typically run a 1/2 dose and change it out every 2(ish) weeks.

 

[exnisstech]

Monthly here if I remember.

 

[Spare time]

Rinse it in scorching hot water in the sink after 2 weeks, replace after 4 total.

 

[tsharpe291]

once a month

 

[hsp]

Thanks, everyone, for chiming in! There seems to be a lack of evidence of what is best. If there is an issue (smell, colouration, etc.) that might impact your actions. Without an acute problem, 2- 4 weeks seems to be the consensus.

 

[Randy Holmes-Farley Verified Community Expert]

So out of curiosity, why 1/2 every 2 weeks?

I change all every 4 weeks, no particular reason. It was stated on one of the brands I used…

Two reasons.

1. It reduces the chance for a sudden drop in light absorbance and hence the possibility of light shock that might come from replacing all of it at once.

2. I was dosing vinegar, and I found the gac seemed to be a place where a lot of the bacteria grew based on what came off as I removed it. I felt that was more desirable than elsewhere in the system, and so wanted to keep it that way. The remaining half acted as seed bacteria to continue the process each time.

 

[Pod_01]

Two reasons.

1. It reduces the chance for a sudden drop in light absorbance and hence the possibility of light shock that might come from replacing all of it at once.

2. I was dosing vinegar, and I found the gac seemed to be a place where a lot of the bacteria grew based on what came off as I removed it. I felt that was more desirable than elsewhere in the system, and so wanted to keep it that way. The remaining half acted as seed bacteria to continue the process each time.

Thank you, I may have to try this.

As to the point 2, I keep GAC in a bag and there is always things coming off. I had impression this was not desirable because it reduced GAC effectiveness. But bacteria is good as well….

 

[Randy Holmes-Farley Verified Community Expert]

Thank you, I may have to try this.

As to the point 2, I keep GAC in a bag and there is always things coming off. I had impression this was not desirable because it reduced GAC effectiveness. But bacteria is good as well….

FWIW, I've used it both in bags and a flow through reactor mixed with GFO. Both work.

 

[xWascallyWabbit]

I try to change mine out monthly but I really just guess and do it when I feel it needs replaced. I'd say 4 to 6 weeks.
Using the brs reactor. Every once I awhile if I need to reduce phosphates I'll put a little gfo in with it. By a little I mean 2 tablespoons. That stuff is potent.

 

[X-37B]

I run 1 liter of carbon in my Avast ozone reactor. I change it every 2 months on my ext 170 display.

 

[MoshJosh]

Wow, I need to start changing my carbon more. . . for those not running it in bags, what is the most cost effective way of changing it that frequently?

 

[X-37B]

Wow, I need to start changing my carbon more. . . for those not running it in bags, what is the most cost effective way of changing it that frequently?

Buy it in bulk. I buy the 5g bucket from BRS.

 

[xWascallyWabbit]

Yep buy in bulk. I would recommend getting a second inside chamber for the reactor so you can swap it out really quick. Clean the older one and set it aside for the next time.
The convenience is just worth it.

 

[jackson6745]

One cup of aquaforest carbon changed weekly with a water change. I just put a sack in a higher flow area of the sump. I think this is a fairly low amount for 300g system. It has no effect on trace amounts according to my last several ICP tests.