Fishless Cycle Question. Carbon?

[ianfarn]

Hello All,

Thanks in advance for any advice.

I've started the wait method of the fishless cycle and have noticed a slight drop in ammonia from the start of 5ppm to about 3ppm. I tested for nitrite and got 0ppm. In the filter there is a carbon section I was thinking this may have caused the fall in ammonia and not the bacteria I am looking for. Is this possible and should I leave the carbon whilst cycling? In fact should I use carbon at all in the filter?

Thanks

Ian.

 

[waterdrop]

There's nothing wrong with having carbon when you cycle, it won't hurt the cycle and won't adsorb ammonia. In fact carbon is technically a pretty good surface media for growing the beneficial bacteria. The problem, and the thing that makes it far from ideal as a biomedia is that it crumbles, getting smaller and smaller and eventually both the carbon dust and the bacteria on that go out during a filter cleaning. By comparison, sponges, ceramic rings, ceramic pebbles and bioballs are a much better choice as a biomedia.

Now, that having been said, what is carbon good for? Carbon is not meant to be a biological media choice, instead its a "chemical media" and its job is to "adsorb" or collect chemicals based on molecular charge. Its used to clear medicines, to clear yellow tannins from bogwood and to clear the occasional organic smell that's unexplained. So its an excellent tool for the hobbyist, but its meant to be stored on the shelf and just used when you have these needs. When you add it to your filter and put it to work it will adsorb for about 3 days and then its ready to be removed and tossed. During the vast majority of time you're running your tank, there's no need to have carbon in the filter.

Why do the manufacturers add it to your new filter? Well, its one of those wonderful "gray-zone" products for them. Its a genuine good thing and so can't be faulted, but many beginners misunderstand it and so will fall for the idea that they need to buy it on a regular basis and keep using it, thus providing steady revenue to the companies. They same sort of misunderstading is used for filter "cartridges," in an attempt to give the feeling that they should be replaced, when in fact that's not what's really needed in a filter.

You say you're doing the "wait method" by which I hope you mean the add&wait method as that's the one we most often recommend. It can sometimes take up to two weeks to see the initial 5ppm of ammonia that you first added drop to zero, but usually its faster than that. So you have to be very patient. As long as you've got some disturbance of the water surface to encourage oxygenation and a good water flow through the filter, the A-Bacs (ammonia oxidizing bacteria) should eventually show up. An ideal temp is 29C/84F and the best pH is 8.0-8.4. You want to be measuring ammonia and pH about once a day initially and recording in your aquarium log. Hopefully you've already got a good liquid-reagent based testing kit?

~~waterdrop~~

 

[rdd1952]

I have read a couple articles (can't locate them right now) that stated that carbon would absorb ammonia. Even if that is the case, it would be fully saturated in a matter of days and then not be removing any, allowing the tank to cycle properly anyway. As WD mentioned, the biggest problem with carbon is that it does become saturated (in anywhere from a few days to a few weeks) and needs to be changed. And of course, when you chnage it, you end up throwing a large portion of your bacteria colony away with the media.

 

[fatheadminnow]

Agree with WD...carbon is only needed to be used when necessary.

But to add on to what rdd1952 said about carbon absorbing ammonia.
My LFS has a huge thank of "feeder" fish for people that ice fish. All they use to take the ammonia and other toxins out is a HUGE bag of activated carbon. So carbon might have some slight effect on ammonia...which would also explain why your ammonia level dropped a little in the first couple days.

But I dont think that my LFS is all that familiar with fish care...lol.

Another thing is that, those "feeder" fish come and go so fast with people buying them all the time, as ice fishing is very popular where I live, that they dont spend a lot of time in the tank.

Just do what WD suggested with the carbon, and all will be fine.

-FHM

 

[waterdrop]

<...>
But I dont think that my LFS is all that familiar with fish care...lol.

<...>
-FHM

have to agree. Finding one of the old experienced LFS owners and then finding which of their "old" advice is accurate is a really hit-or-miss thing. Its out there though and I'm not one that thinks LFS's should be universally disparaged, as many small locally owned ones have people that have put their lives into it and love the hobby. That said, though, usually the level of accuracy and detail found here on TFF on fish care just blows away what you'd get on average from a LFS.

~~waterdrop~~

 

[OldMan47]

Once you understand how carbon works, many things about it become clearer and many of the often cited "facts" about carbon become more tentative. Carbon works through adsorption, not absorption. Things tend to cling to the surface of the carbon but each chemical has its own attraction to the carbon. Carbon does not chemically react with any of the chemicals that we try to control with it. The sequence can best be thought of as having something stick to the carbon until something better comes along. Better in this case means it is more strongly attracted to the carbon. When something better comes along, the first thing sticking to the carbon is released in favor of the new item. Where that puts you is simple, when carbon is first placed into the water, anything and everything that touches the carbon will be adsorbed. In a very short time, all of the adsorption sites will be filled. At that time, whatever is least held to the carbon will start to be released back into the water as things that have a higher attraction come along. In turn each thing that is attached to the carbon will eventually be displaced by something else with a higher attraction to the carbon until the whole carbon bed is covered with the one thing most attracted to the carbon.
I have simplified things a bit but that will give you the essence of how it works. That means that anything you want to remove from the water can be removed using carbon if you are willing to replace the carbon often enough. It also accounts for the people that say carbon is exhausted in a few days while the filter makers only recommend replacing it once a month, they are not looking at the carbon's effectiveness in the same way. Stories of carbon releasing whatever is on it are also partly correct because it will do just exactly that when something comes along that is more strongly attracted to it. You can almost think of carbon like a sponge, once it is full, the only way to soak up more is to first wring it out.

 

[rdd1952]

Good explaination OM47. I had originally put adsorbed in my post but didn't want to get in the the difference between "ad" and "ab" since most people seem to always use "ab" even though it should be "ad" (almost the same way shoaling and schooling are used). I think you explained it very well.

Bascally though, I think that is exactly the reason that when a fishless cyclle is first started, the initial ammonia drops pretty quickly with no nitrite showing up. That is simply a matter of the activated carbon handling it until something better comes along. Does the ammonia ever get released back into the tank? Who knows since we (or the fish in a fish-in cycle) are adding ammonia back in anyway.