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Second is contact time. Slower flow allows better contact time and removes more efficiently. Also prevents premature clogging because moving less volume through the filter means it will pick up less particles. Remember carbon and GFO are removing molecules, very tiny things, let the skimmer and filter socks pick up the larger particles they just clog the carbon and prevent it from being the most efficient.
I certainly agree that one needs to be careful when first initiating GAC to reduce the risk of light shock when reducing yellowing.
But I can't agree with the idea that increased contact time is desirable for most efficient use of carbon. Some hobby authors also get this wrong, and maybe that's where it first came from. I argued with one of these folks quite a bit.
It would absolutely be true that increasing contact time would have no effect or would improve the rapidity that GAC binds organic matter from seawater IF it was a one pass system. BUT IT IS NOT, it is a recirculating system.
So lower contact time just means you are bringing in dirty (dirtier) water faster. The actual "contact time" of the GAC with the water is 100% of the time. It is always in contact with aquarium water.
The thing that then becomes a factor is the concentration of organics in the water. The more organics in the water, the faster the GAC will bind them. The faster you replace the clean water near the GAC with dirty water from the aquarium, the more organics will be bound over time. Faster flow also reduces the "dead zone" at the surface of the GAC, thorough which organics must diffuse as opposed to be carried by flow.
Of course, there are limitations to this analysis. You do not want flow so high that there are undesirable things happening, such as the GAC getting beaten to bits, channeling through the carbon, air or debris getting into the GAC bed and clogging it faster, etc. The flow analysis also suggests there is a plateau effect, when the incoming dirty water is only very slightly more dirty than the water leaving the GAC, at which point, higher flow doesn't improve binding rates.
Ok, this makes good sense. Since it is a recirculating system contact time is not relevant, more flow increases organic concentration and bind rates with the GAC.
Thanks Randy!
@Randy Holmes-Farley I guess what I'm asking is there any other negative effects carbon can generally cause besides sudden light shock from the clarity. I generally only hear great things about carbon.
I run about 2 cups in a brs reactor and everything's good in my tank....so far.what are your thoughts on using this carbon with sps? I tied to use it about a year ago in a media reactor at half the recommended amount and after using it I got some some stn a couple of days later. I am wanting to use it again but am scared to use it.
If your using have you ever ran into problems?
You might want to dial down the intensity of your lights and/or let your alk come down.Any followup to this post? I started running rox.08 and now two weeks later am experiencing burnt tips with algae growth on them, Along with several RTN. Nothing else has been changed in the last 3 months. Lost my big Cali tort colony that has been growing at the top of the tank for 2 years. (I didn't think anything could kill that).
SPS dominated tank, with many colonies and frags. Tank has been up and running successfully for 4 years. (140 gallon total water volume) Previoulsy ran bituminous carbon 2 cups in a reactor 24/7, changed out monthly. I ran the ROX 1 cup for the last 2 weeks.
I run 3/4 cup in my system that is roughly 200 total gallons. Rox is potent stuffAny followup to this post? I started running rox.08 and now two weeks later am experiencing burnt tips with algae growth on them, Along with several RTN. Nothing else has been changed in the last 3 months. Lost my big Cali tort colony that has been growing at the top of the tank for 2 years. (I didn't think anything could kill that).
SPS dominated tank, with many colonies and frags. Tank has been up and running successfully for 4 years. (140 gallon total water volume) Previoulsy ran bituminous carbon 2 cups in a reactor 24/7, changed out monthly. I ran the ROX 1 cup for the last 2 weeks.
Any followup to this post? I started running rox.08 and now two weeks later am experiencing burnt tips with algae growth on them, Along with several RTN. Nothing else has been changed in the last 3 months. Lost my big Cali tort colony that has been growing at the top of the tank for 2 years. (I didn't think anything could kill that).
SPS dominated tank, with many colonies and frags. Tank has been up and running successfully for 4 years. (140 gallon total water volume) Previoulsy ran bituminous carbon 2 cups in a reactor 24/7, changed out monthly. I ran the ROX 1 cup for the last 2 weeks.
Run rox at half the amount you need. Same goes for high capacity gfo or any gfo for that matter.