How long does a new tank cycle normally take?

I had a 90L tank for two axies but it was getting too small and one was nipping the other, so I bought a new 130L tank and am in the process of cycling it.

To this new tank I've added three fake plants from the old tank, the filter and its media from the old tank, several other items from the old tank (log to hide in etc) and about 50% of the old tank sand substrate, with some new sand.

I put a dead prawn in 2 weeks ago and the ammonia level quickly ramped up to about 3.5ppm-4ppm.

However, it's stayed at this level for 2 weeks now without moving. Obviously I can't put the axies in there yet but I've read elsewhere cycling takes about 2 weeks, and mine doesn't seem close to ready yet. The prawn is still in there as a source of ammonia. Is there anything else I should be doing? Water changes?

Thanks.

If you're doing a fish-less cycle then water changes aren't needed. I think 2 weeks is actually the minimum for cycling a tank and it could take a month or more. I would just check the ammonia every few days or something just to see what's up. Have you checked the Nitrites and nitrates?

Thanks for the reply. Nitrite level is basically 0 (light blue in colour in the testing kit). I guess I just to have to wait longer.

I would think so too. I would just check the ammonia every now and then to make sure it stays up and test the nitrites again in a week or 2 to see if anything has changed.

You can put a heater in to speed it up. The warmer it is, the faster it will cycle. Cold water tanks take a good bit longer in my experience.(about 35 years worth....lol)

Someone let me know if I'm missing something, but since you took the old filter along with the old media from the old tank, along with a good amount of the substrate, that it would have been "cycled" anyway? If you had taken all of the contents of the old tank and moved them to the new, that the only surface area for the nitrifying bacteria to cling to that would be missing would be the tank walls, which are negligible relative to the filter media/substrate/etc.?

How are the parameters of the existing tank doing without the old filter and media?

Yes, If the filter is moving to the new tank it is essentially instantly cycled. Assuming that you have not let the filter dry out, change your filter media, clean out the filter, etc.

There will be a minor spike because of the water change but it isn't enough to do harm.

OK - seems logical I guess; I was under the impression the bulk of the good bacteria exist on tank walls, and as this new tank is pretty substantial in size I figured I needed time to build up the biolfilter on the walls.

The ammonia levels are still at about 3ppm after two and a bit weeks. I might remove the dead prawn, test out ammonia and nitrite levels over the coming week, do a small water change and see what the chemical levels are like in that case.

I appreciate all the advice - thanks.

Xtophr said:

Someone let me know if I'm missing something, but since you took the old filter along with the old media from the old tank, along with a good amount of the substrate, that it would have been "cycled" anyway? If you had taken all of the contents of the old tank and moved them to the new, that the only surface area for the nitrifying bacteria to cling to that would be missing would be the tank walls, which are negligible relative to the filter media/substrate/etc.?

How are the parameters of the existing tank doing without the old filter and media?

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The existing tank, with new filter and one remaining plant, is doing fine - no ammonia, no nitrites.

What kind of media does your filter use? Is your filter made for a smaller tank or does the tank it's on now fall into it's GPH range?

If you're using an old filter cartridge, if it's one of those little sacks with carbon on it I'm not sure how much bacteria that would hold. You could cram some extra filter floss or filter sponge into any gaps inside the filter, or on the intake, or in the outflow of the filter. All of those would help it hold more bacteria.

I don't know if that's what you're going through but my first tank had a little filter with a tiny little sponge. After I replaced it with an aquaclear and a floss/sponge/ceramic media combo my tank cycled in like a week after about a month or so of no cycle. The older one would just gunk up and require cleaning too often.