New Tank (Fish In Cycle)

[lizandel]

Hi, just wondering if someone can help me understand what is happening in my tank. I started my tank almost 3 weeks ago. It is about 20US gallon and it is octagonal. I also realise it is best to cycle without fish but ammonia is impossible to find here is Aust and I didn't realise you could use fish food or some other ammonia source at the time.

Anyway I added 6 harlequin rasbora almost 3 weeks ago. I set my tank up probably almost two weeks prior to that with a sand substrate and I added a mature anubia attached to some driftwood also. I also have a couple of corkscrew vals, 3 banana lillies (which are growing very fast), java fern, java moss and amazon sword.

Since adding my fish my ammonia levels have not gone above 0.25. I am using an API kit. However for the past around 10 days my results for ammonia have been 0. Up until last Friday I had been doing daily water changes of around 15%. Since then I have done a water change on Monday and am doing another one today.

My current water stats are as follows:
Ammonia: 0
Nitrite: 0
Nitrate: 5
pH: around 7.4 (seems to go as high as 8 and low as 7.2)

I do not have a hardness test kit.

I realise there is no way this tank is anywhere near cycled but don't understand why I have no ammonia or nitrites but I have a nitrate reading. I tested my nitrates at the start and retested my tap water when I realised I had a nitrate reading in my tank and both times the tap water was 0ppm for nitrate. I hadn't been worrying about testing for nitrates as I had had no reading for nitrites but just decided to test it anyway about 5 days ago. My water has been maintaining 0 and nitrite ammonia without daily water changes. Just wondering what others think. The fish seem to be very healthy, their colour is lovely and they are very active currently.

 

[arobinson1984]

I'd hazard a guess that the amount of live plants that you have in the tank are absorbing the small amount of ammonia that is being created by your fish.

Personally, I never keep plants in the tank during any type of cycle as they can have an effect like you are seeing. If you are planning on adding more fish to the tank then I'd add them a few at a time and keep an eye on your test results. Alternatively you can remove the plants until the cycle is completed.

Andy

 

[timmystood]

It's sounding great!
The reason why you are not reading any Ammonia or Nitrite is because the filter is now capable of coping with the waste produced by your 6 fish. Therefore, if you weren't adding anything else then your tank is cycled. However, I would guess you are wanting to add more and so the tank will still need some maturing. The only way now to properly increase the bacterial supply in the filter is by adding more livestock.
Your doing everything right and the daily water changes would have ensured that the fish weren't affected by any ammonia/nitrite spikes while the tank was cycling. From now on I would suggest adding more stock every 2 weeks (with perhaps 2 water changes a week) until your fully stocked.

 

[arobinson1984]

I don't agree that the tank is cycled.

The op said that the ammonia levels have never gone over 0.25ppm, which would be VERY unlikely with only 15% daily water changes.

I'm sticking by my theory that its your live plants and not the filter that are consuming the amount of ammonia produced by your fish, or possibly a combination of both but I'd be very sceptical to call the tank 'cycled'

I'd put money on a large ammonia spike in them plants were removed.

Andy

 

[timmystood]

The amount of Ammonia absorbed by plants is minimal. I agree with you in as much as it will help but with adequate filtration and only 6 small rasboras in a tank that size, I wouldn't expect Ammonia to ever go above 0.25ppm, espically with the daily water changes.
I didn't say that the tank was cycled. What I said was that the tank is able to cope with the stock currently in the tank and is therefore cycled with the stock it current holds.

 

[OldMan47]

The amount of ammonia absorbed by plants make it possible to set up a new tank, add plants and fish and never see any ammonia. It has been done and is done intentionally in some methods of fish keeping. It requires that the plants be growing vigorously and the tank not be overstocked with fish, but it can work. This is a so called silent cycle that is well known among plant people, who are always pushing their plants for high growth rates. Something to be careful about,if you are in this situation, is adding more fish. Because the bacterial colonies have not been established and you do not know whether there are any bacteria in your setup, you do not know if it is safe to add anything at all to the tank stocking levels.

 

[lizandel]

Thanks for the replies. From what I have read I thought this was the case but my only confusion with this is the nitrate levels. Where does that come from?

I was not planning on adding a whole lot more fish to this tank. I am hoping to add some cherry shrimp and some kuhli loaches at some stage. I am hoping to get a bigger tank (6ft), this tank I am using is one I have had for years and didn't use for a long time because it had a leak in one of the seals.

 

[OldMan47]

Plants will absorb ammonia before nitrates based on their own preference for ammonia. If there is any nitrate present, it would mean to me that the plants are getting all of the nitrogen that they need from the ammonia. In practical terms that means you need to be even more careful about increasing the biological load.

 

[waterdrop]

Can't disagree with any of the angles here. OM47 is right that there's every reason to go very slowly and lightly with added stocking here as you could probably quickly find out the colonies are not as far along as you think. I also agree with timmy that its going along nicely and between the fairly light stocking, the plants and the water changes you appear to be doing the right thing for a fish-in cycle. It will probably drag out for a long time but as long as you're ok with only adding slowly, things should be fine.

~~waterdrop~~

 

[lizandel]

Thanks for everybodies help and suggestions. I have decided not to remove the plants and to only add more fish slowly at some stage. Not really a problem as I live about two hours from a decent LFS so no temptations around here! I am still really undecided about what else to put in there at the moment anyway.