OK, compadres. I know all of the good things carbon is supposed to do. I also know that the expert fishkeepers in Asia use carbon on their Koi aquariums since Koi produce astronimcal amounts of ammonia, even in comparison to Goldfish. I know a lot of people use carbon with success with Goldies, too.

What I want to know is the rationale behind the decision for those of you who DON'T use Carbon?

I used to use it with no consequence on my African Cichlid tanks. I have not used it with Goldfish until three[or so] weeks ago. At that time, I removed the river rock from my main tank, leaving all substrate/biomedia intact in my sump and wet/dry filter attached to the main tank. The water got a little milky so I used a clarifier [once] and added carbon to my filters. Ever since, I have been registering 0.25 for nitrite. I know that's low and is managable, but it should not be there. I've always registered 0, before. Ammonia returned to 0, the day after the river rock was removed so nitrosoma colony is intact. Something... either the addition of carbon to my filters or the [one time] use of a clarfier... has wolloped my nitrobacter colony. I won't blame the removal of the river rock, because of the amount of subtsrate/bio media in the sump and wet/dry filter.

It seems more likely that the clarifier is the culpreit here. As I said before, I used carbon for years with African Cichlids, with no problems. But I won't rule out the addition of carbon as the culpreit [or co-culpreit] until I have heard why some folks refuse to use it in their systems. The fish are not stressed. I think Wakin could live in a ditch and not complain. I borrowed some substrate/media from my other tank where all params are normal so I am certain that nitrobacter is re-introduced at present. But I want to make sure this incident is not repeated.... esp. before I recommend anyone else go "barebottom" from a tank with bottom substrate and *normal* params, use a clarifier or tell them carbon is OK on a Goldfish system.

Other params:
280 gallons total volume.
fishload: two, 7" Wakin
tap water params: everything at 0
ammonia: 0 ppm
nitrate: 0 ppm [frustrating] - was registering normal nitrate before the above events.
pH: 7.8
I do not routinely measure KH
water change frequency: 100 gallons every two to three days at present so nitrite stays at 0.25 max.

KoKo, I know you'll want to move this post to the appropriate place but I humbly request it remain in this less obscure forum location [if it is no bother] until a number of folks have had a chance to read it and possibly, respond. As always, thank you for KoKo's!

Cometkeeper:

Many aquascapers don't like to use activated carbon because it removes some of the trace elements and nutrients that are good for the plants. Activated carbon works great to remove many contaminants from the water. It also provides surface area for the growth of bacteria. Nitrobacter should not be affected by the addition of AC. My guess is that by removing your river rocks you also removed a lot of biofilm from the tank upseting the biological treatment. This was then observed when you saw the bacteria growing in suspended form (turbid water). The bacteria in your filters will eventually grow to levels that can keep nitrite at zero ppm.

Don't blame the carbon... AC Rocks!

Thanks, Kingyo. It didn't make sense to me that the carbon was the culpreit, but I am going through a process of elimination.

I do believe something happened other than just the biofilm being disrupted, though. l have tons of undisturbed substrate in the attached sump and wet/dry filter. And my nitrate level went to and has stayed at 0 along with a rise in nitrite level, signifying that the nitrobacter colony was possibly wiped out or nearly so. Three weeks now... and no nitrates. Nitrate level was typical prior to these three events: removed river rock which was perhaps 30% of the total substrate volume in the system. Used clarifier. Added carbon. In three weeks time of eleveate nitrite/zero ammonia, if even trace nitrobacter had been spared, we'd be seeing SOME nitrate production. I don't know. It's a real head scratcher. I won't blame the carbon, but I sure won't be using a clarifier ever again.

After following another somewhat related thread, I now suspect that the prolonged nitrite spike/dip in nitrates I am experiencing is the result of changing too much water in an attempt to keep nitrite at or below 0.25 ppm [roughly 30% every couple of days]. I may never know for sure what wiped out the nitrobacter colony in my aquarium but am quite sure that is what happened vs. a mere disruption of the biofilm when I removed part of my substrate. At any rate, I am going to try Prime and salt [vs. frequent water changes] to help ease my fish through this nitrite spike, thereby allowing the nitrite level to remain elevated [albeit in a safer form] until the nitrobacter colony can proliferate. Again, I introduced some media from my **normal** aquarium [the one that gets less attention!] so I know the nitrobacter is at least present, now. Am going to trust another member who suggests that bound ["Primed"] nitrite is going to register normally, meaning that all the purple I see in my test tube is actually going to be safe <sigh> for my fish... New concept for me, but I'm willing to give it a try since the frequent water changes really seem to be prolonging this stage of the cycle. Or should I say "re-cycle" after an unexplanable crash.

If the levels of nitrite get especially high, you may want to double or triple the Prime dose.

Good luck on getting your bio-colony setup again!

Our Aussie friend, Fishermaid, seems to be the Queen Of Prime <g> and what she has recommended is the following:

test daily
nitrite 0-1 ppm - no water changes; Prime at 50% usual dose.
nitrite 1-2 ppm - no water change; Prime at 100% usual dose.
nitrite 2 ppm + - 50% water change and Prime at 200% usual dose.

Her rationale makes perfect sense. What Prime is not used up by binding to nitrite will remain in the water for available nitrite to come along. While up to 5X the strength [as recommended on the bottle] in emergency cases is OK, this is not good to do routinely. Since one will be adding Prime daily through this phase of the cycle, a higher dosage of Prime than 2X is overkill.

Consequently, with most nitrite test kits, "Primed" nitrite will still register as being present. However it will be in a bound form that is still bioavailable for nitrobacter, but harmless to fish. prime does not starve nitrobacter. I am doing this and my fish are fine - no apparent signs of stress at all.

Who says you can't teach an old dog, new tricks? Just kidding. I am convinced that fishkeeping is a dynamic endeavor. What works for us today will not neccessarily work for us in three months. Our methods constantly evolve.