Carbon in bag or reactor?

[Woofwoof]

Hey all, I just got and set up a BRS single media reactor. I also got BRS GFO and BRS ROX .08 carbon. I Planned on running the gfo and carbon in the same reactor, but at the last minute after looking online it looked like it might not be a good idea to run both in one reactor, especially the ROX. I put the gfo in the reactor and put the ROX in a bag near my overflow into my sump. What do you recommend? Can I run both in my reactor and if so how should I set it up? Can I just leave the ROX in the bag, will it make much of a difference in a reactor over the bag? Should I try to squeeze another reactor into my stand? It seems like such a waste of space in the reactor to have such a little amount of ROX in the reactor. Thanks for your help.
p.s. The tank is a 65 with a 29 gal sump, reef ocotopus 150, quiet one 3000 return, lightly stocked mixed reef as I moved over from a BC29 over the past few months.

 

[inverted]

It's best not to run GAC and GFO together. GFO needs to be tumbled, but GAC will get pulverized at that flow-through rate. Also, GFO lasts about twice as long. GAC works by surface adsorption, so, it is not necessary to force water through it, but it does work more efficiently if water is forced through, as the water is forced to contact all of the available surface area. So, just take that into consideration, but there are many ways to run GAC.

 

[KSC]

Many people run gfo and carbon together. As stated above, it's probably "better" to run it seperately, but only having to change out one reactor once a month or so instead of 2 reactors makes it easier. Here's some good info on gfo/carbon/reactors...

http://www.bulkreefsupply.com/store/brs-tv/carbon-gfo-videos

 

[inverted]

That's fine, but keep in mind GAC will only last 1-2 weeks. Even if you don't exhaust it, it gets junked up with bacteria and then doesn't tend to work well. If you change it out monthly, your basically not running GAC for 2-3 weeks out of the month. GFO can last a month though. So, if you change it out every two weeks, your likely discarding perfectly good GFO. Depending on your goals, one of these scenarios may be fine. I run them separately though, as I get best results changing spread out GAC weekly and find no difference with GFO if I only do so monthly.

The other issue to changing out GAC infrequently is that bacteria growing in coral mucus is sensitive to organic carbon fluctuation. GAC effects organic carbon levels more than any other mechanical filtration. So changing it out infrequently is more likely to cause fluctuations, which can be detrimental for well understood reasons.

Sent from my iPhone using Tapatalk

 

[KSC]

Some might not agree. Figuring out when either your GAC or GFO is exhausted is probably not worth the time and effort. There was a guy on RC that had really high p04 and did an experiment. At the beginning his GFO was exhausted in about 24 hours....


Randy Holmes-Farley
Reef Chemist Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 52,068

What is meant by "Activated Carbon"?

It is a form of carbon with a very high surface area for absorbing organic molecules and catalyzing certain chemical reactions (like chlorine and chloramine breakdown).

I don't think that any organics are released by activated carbon unless they are being replaced by other organics. So the idea that things will eventually be released is not something to worry about. However, just like a kitchen sponge, it will eventually be "full", or more correctly, fully covered with organics. At that point, it is essentially useless.

So at some point, it needs to be replaced. How fast that is depends entirely on the flow over the carbon, and the level or organics in the water. I don't really have any opinion whether 5 days or 4 weeks is better. To some extent, I think it depends on how agressive you want to be in removing organics, and how much money you want to spend.

FWIW, I don't think you can really overdo carbon, within reson.

Carbon works because its surface is hydrophobic (like an oil). Organic molecules in the water that are wholly or partially hydrophobic will "want" to attach to this hydrophobic surface, and become stuck. Not all organics bind to carbon at all, but many will.
__________________
Randy Holmes-Farley

 

[inverted]

Yes good point, i should clarify. My example was going off you comment about changing out the media monthly. However, certainly if phosphate is high, or insufficient GFO is used, the GFO can be exhausted quickly. If you add more though, it will last longer. For GAC this is true to a point, adding more can make it last longer, but not the same as GFO. Once bacterial biofilms start to colonized the GAC, it becomes fairly ineffective, so, from my understanding, the longest it tends to last is 1-2 weeks. Some say less. So, the point was you can't easily make GAC last a month, but you can make GFO last a month just by adding more.

For GFO it's fairly easy to tell when it's exhausted. You can use a Hanna checker and watch the film algae growth on the glass. Neither is perfect, but together they provide good hints.

For GAC there is no reasonable way to test organic carbon levels unfortunately. However, I find certain corals, especially some LPS corals will start to shrivel up a bit when GAC starts getting old. Usually they perk right back up after changing it out. Not great but seems to work for my purposes...

Sent from my iPhone using Tapatalk

 

[inverted]

Also BTW, I'm assuming your not cleaning the GAC. Rinsing GAC and crushing it up a bit can greatly extend the life. It's tough to make relatively brief comments without making some assumptions, so there are certainly exceptions to my statements....


Sent from my iPhone using Tapatalk