2lucky

Well I have had my 107 gallon running for a couple of monthes now and it was cycled...
I've had fish in their since it was cycled and all seem fine and healthy.
I've always had 0 amm, 0 nitrates and 5 trates since it cycled...
I tested it again yesterday after being on holidays for a week and now I have 0 nitrates!
Is it common for a cycled tank to have 0 nitrates? Or does it mean that the cycles failed and I have to start again? Keep in mind I've had fish in their all the while and there's no reason for the bacteria to die...
The only thing I did do was remove the carbon in the filter a couple of days before going away.

Thanks for the help!

agabr123

did you test everything else? still 0 ammonia and 0 nitrite?

i would keep an eye out for an ammonia spike, if you get one, something triggered a mini-cycle, possibly a medication or if you added a significant number of fish recently?

it's possible the cycle failed, but a mini-cycle is more likely IMO, what kind of filter(s) do you have?

Nick G

What else was in the Filter, besides the Carbon?

2lucky

The readings are: pH=7, 0 amm, 0 trites, 0 trates. tested with API master kit. I tested yesterday
The filter's an external canister that does 2400 litres per hour, it has heaps of other filter media in it: sponge, bio-rocks etc.

I haven't been using any medication, and have been adding fish very slowly. All the fish are relatively small, too. So IF it is a mini cycle what could have triggered it?
Also, IF it is a mini cycle what do I do about it? 50% water changes are not possible in my case.

Lucy

It's possible to have 0 nitrates if you have a heavily planted tank.
If you're using the API Master kit, the #2 nitrate bottle needs to be shaken, banged and whacked on the counter to get the crystals to mix together and get an accurate reading.

agabr123

since 50% water changes aren't really accessible for you having such a large tank, i'd put your fish in your QT if you have room and if you don't have live plants in the 108.

if it IS a mini-cycle i'm not sure what could have triggered it since its such a large tank and you only have small fish in there right now, unless a significant amount of the media was changed then i'm not sure.

i'd keep testing for ammonia daily until i knew what was wrong, that way, if it is a mini-cycle you'll be able to catch it immediately and quarantine your fish, and otherwise just keep an eye on things.

if you have live plants, like lucy said, that could cause the nitrates to be zero.

Butterfly

Were the fish fed while you were gone ?If not there would be less waste.
Plants will suck Nitrates right up. If planed heavily at the beginning you may never see Nitrates or the normal cycling behavior. It's called a "Silent Cycle"
Carol

2lucky

Thanks guys.
Tested again today -0 ammo, 0trites, 0 trates again.
There are 6 bunches of different plants in the tank -do you think that would be enough to cause a "silent cycle"?. And the fish were fed twice a day while I was away -not too much though.
Also I did shake the bottle 'vigorously' for the 30 seconds advised. Didn't bang it on the bench though . I dont think that an inaccurate testing is the case coz I've tested before and it's shown up 5 nitrates.
Again, thanks for the help!

Mike19

Maybe its worth a shot just to bang it, to move the crystals around

2lucky

Yes I will certainly to that next time. I didn't know is all...

pepetj

Your bioload is likely negligible for the volume of water you have. If you keep a healthy maintenance routine in your canister filter, you should expect to see some, but still low, readings on nitrates once your bioload increases.

Just for comparison purposes consider the following (my experience):

In a 145gal tank, with likely 120gals of water, natural river sand substrate and three AquaClear 110 as filtration, I keep two young adults Tiger Oscars (12-1/2" long each), two young adults Heros Severum (8" each), four young adult Convict Cichlids (3 to 4" each), and their fry (around 20 juveniles 1/2-1" each), as well as five young adults Kenyi (at 4-5" each) and some fry (around 10 juveniles 1/2" each).
Sidenote: juveniles in that tank are there because I have poor success netting them out!

I kept this tank moderately planted since I set it up in July 2008, I upgraded lighting (a work in progress really, I did it slowly in order of not disturbing my fishes) and in December 2008 I planted heavily with surface-floating plants (water orchids, water lettuce and earmoss) covering 2/3 of the tank surface, as well as potted submersible plants (anacharis, hornwort, hygrophila, vallisneria) and some that eventually emerse (parrot feather).

Before I went heavily planted, my nitrates, in one week reached 20ppm or even close to 25ppm if I overfed, in two weeks it would go close to 40ppm. As I added more plants (took me some time and lots of trial and error since Oscars live there) it stayed around 10ppm a week after water change, and reached 25ppm in two weeks time.

Now I am having negligible readings in nitrates (5ppm or less). The nitrite/nitrate test strips that I use for screening show 0 on both (Tetra 5-in-1 and Jungle). I might do water changes every other week if I keep obtaining readings like these. I use Marine Enterprises Inc Nitrate test and the nitrate test from API FW Master test kit.

Also I use fertilizers that contain no nitrates or phosphates.

Pepe
Santo Domingo

agabr123

that's true...i hadn't thought about that. since you have so few fish in your tank and it's so huge, chances are there just isn't enough of a bioload. you COULD run into problems when you try to add more fish, since it will be hard for the tank to keep up if you're adding anyone that produces a lot of waste, but if you just add very slowly and spread it out, you should be okay.