4 wks into cycling

[NYG 010]

Hey guys I'm about 4 weeks into cycling now with live rock and live sand. When do I know I'm positive to add a fish? I've been checking my levels and the only thing thats a little spiked up is my nitrates right now at 20 ppm (Note: I have not added chaeto yet) my light comes in about a week ..so Do i wait?

[Stasiu]

20 ppm of nitrates is fine to start fish in. I'd start with one or two small fish at this point.

[NYG 010]

I'm thinking of adding One black clown percula and one regular percula..Whats a bad range for nitrates?

[NYG 010]

and do you think those 2 will be fine in a 10 gallon. It will be the only fish

[Aquarist007]

Originally Posted by NYG 010

and do you think those 2 will be fine in a 10 gallon. It will be the only fish

having that level of nitrates indicates that the bacteria have not fully cycled yet. In a 10 gal tank I would wait until 0 nitrates before adding a fish and when you add the two clowns---one good week between adding each.

Your tank will support two clowns providing you do weekly 10 per cent water changes and you have 10 lbs of live rock

[NYG 010]

Capn can you give me more info on what you mean by the bacteria havent fully cycled yet? Thanks for all your help! I have about 13+ lbs of live rock in already.

[NYG 010]

And wont adding the fish a week later make them more prone to fighting with each other? If i add them both wont they have less territorial issues? I'll get one a little bigger than the other

[Aquarist007]

Originally Posted by NYG 010

Capn can you give me more info on what you mean by the bacteria havent fully cycled yet? Thanks for all your help! I have about 13+ lbs of live rock in already.

There are three types of bacteria involved in the nitrogen cycle. Aerobic and two strains of anerobic bacteria. The second strain of anerobic bacteria(anoxic bacteria) are responsible for reducing nitrates to harmless nitrogen gas and thus completing the nitrate cycle. These bacteria can only exist deep in the live rock and deep in the sand bed. They are usually the last to cycle or increase there numbers--when they have the nitrogen levels go down to zero.
By monitoring ammonia nitrites and nitrates you are really monitoring the growth of aerobic and anerobic bacteria. When the ammonia nitrites and nitrates are zero then the bacteria have multiplied or cycled enough to handle the existing bioload in your tank. Since you have nitrate readings still then your tank is not ready to handle the existing bioload of your tank.
If you add a fish at this point you are going to further add a bioload to your tank when the existing bioload is not under control yet by the bacteria. This could cause an ammonia spike and kill the fish and or other inhabitants in your tank

[NYG 010]

Right, I'm going to wait for my Nitrate to drop then add the fish (maybe after a week). Does that sound alright?

[Aquarist007]

Originally Posted by NYG 010

Right, I'm going to wait for my Nitrate to drop then add the fish (maybe after a week). Does that sound alright?

you are pretty close---its good to be patient

add "a fish" singular form

[NYG 010]

Well the reason why i said add the "fish" (plural) was because I heard if that if I add both clowns at the same time then they will have less territorial issues...resulting in less aggressiveness.

[Stasiu]

I didn't realize the tank was only 10 gallons. I'd definitely wait another week for the nitrates to drop, and when they do only add one fish at a time as mentioned before.

[Lemeshianos]

Capn, if we wait for nitrates NO3 to drop to zero, wouldn't the other bacteria(that break NH4-> NO2 and NO2-> NO3) starve in the meantime?
Meaning that at some point we might have bacteria that reduce NO3 but not enough to properly handle ammonia and nitrites because of die-off?

Also I've been reading on RC for a couple of years and I was under the impression that the number of bacteria that reduce NO3 is much less than the number of bacteria that convert ammonia to nitrites and nitrites to nitrates. What I mean is even if we feed the tank with ammonia(whether it is direct ammonia or food) to keep the other bacteria alive, the number of NO3 will always be higher than zero.

Maybe I'm confused, can you please explain?

[wooden_reefer]

Originally Posted by NYG 010

Hey guys I'm about 4 weeks into cycling now with live rock and live sand. When do I know I'm positive to add a fish? I've been checking my levels and the only thing thats a little spiked up is my nitrates right now at 20 ppm (Note: I have not added chaeto yet) my light comes in about a week ..so Do i wait?

Did you test for ammonia and/or nitrite?

Time of four weeks and current nitrate level does not generally tell us if the tank is cycled.

If you test nothing for ammonia and nitrite, it is either very good or very bad, meaning that either the LR has been cycled before you put it in OR there is no cycling at all, no ammonia to start with. However, if you detect a sharp nitrite peak and now it is gone, this is a strong indication that your cycle is complete.

Actually, nitrate could be a flimsy indication. If the fresh water that you mixed the salt with (I suppose this is how) has little nitrate, and yet there is much more nitrate now, this is a non-standard indication that the cycle is done. THis is a little chancy way to tell but it is not groundless althogether. What is the source of the nitrate?

[wooden_reefer]

Originally Posted by capn_hylinur

There are three types of bacteria involved in the nitrogen cycle. Aerobic and two strains of anerobic bacteria. The second strain of anerobic bacteria(anoxic bacteria) are responsible for reducing nitrates to harmless nitrogen gas and thus completing the nitrate cycle. These bacteria can only exist deep in the live rock and deep in the sand bed. They are usually the last to cycle or increase there numbers--when they have the nitrogen levels go down to zero.
By monitoring ammonia nitrites and nitrates you are really monitoring the growth of aerobic and anerobic bacteria. When the ammonia nitrites and nitrates are zero then the bacteria have multiplied or cycled enough to handle the existing bioload in your tank. Since you have nitrate readings still then your tank is not ready to handle the existing bioload of your tank.
If you add a fish at this point you are going to further add a bioload to your tank when the existing bioload is not under control yet by the bacteria. This could cause an ammonia spike and kill the fish and or other inhabitants in your tank

It is a matter of definition and it is also helpful in practical ways as well.

IMO, the term cycle refers to nitrification only, not denitrification. Cycling is the cultivation of nitrification bacteria, ideally a lot of them.

Cycling, by definition, does not involve denitrification.

Definitions helps communication among aquarist.

It is also practically helpful to have clear definition.

When I say the medium for QT of fish should be cycled, I mean it should have nitrification. Denitrification is generally not important in QT.

It is not that I don't think denitrification is very important in a DT. Denitrification is important for long term stability and balance in a DT, but still "cycling" is the cultivation of nitrification bacteria and only nitrification bacteria.

Nitrate is not toxic to fish except in quite high concentration so some nitrate in QT for fish is quite acceptable.

The message lost here is also QT. The whole discussion should be where is the QT and how has it been cycled. The DT is not relevent here yet.