Well The Theory Was Fine......

[the_lock_man]

I have a 65l, which is somewhat overstocked, but the filter has been cycled and stable for 6 months or thereabouts.

Santa brought me a new 34l, and I thought that if I put in a sponge and about a third of the ceramic noodles into the new tank's filter from the older tank, I would have enough bacteria for one fish in the new tank.

It seems I do have enough A-bacs, but I'm showing some nitrite.

The full stats, as at this morning are

0ppm ammonia
0.2ppm nitrite
40ppm nitrate (compared with 30 in tap water)
pH 7.8
temp 26C

I obviously have some N-bacs, since I have more nitrate than in tap water, but not enough to do the job completely.

So do I

(A) Move some more filter media over (risking the stability of the other tank)
(B) Soldier on with a fish-in cycle
(C) Move the fish over to the older tank, (which is the long-term objective for that fish) and switch to a fishless cycle
(D) As above but also move the mature media back again, and start again with a fishless cycle from scratch
(E) Any other options?

As always, all advice gratefully received.

 

[Uriel]

C.
Why risk you fish in your established tank by taking out to much media and why expose this new fish to unnessacary stress of a poisonous enviroment. Plus you save yourself the hassle of having to do lots of water changes to maintain a fish in cycle. Also using mature media most fishless cycles only take a week.

 

[Skins]

C.
Why risk you fish in your established tank by taking out to much media and why expose this new fish to unnessacary stress of a poisonous enviroment. Plus you save yourself the hassle of having to do lots of water changes to maintain a fish in cycle. Also using mature media most fishless cycles only take a week.

B or C, if you opt For B just keep up with your water changes/gravel vacs, your nitrite levels proberly won't take long to go to zero.

Keith.

Ps your current nitrite levels are not perfect but then are no way critical, so small frequent water changes will be ok.

 

[waterdrop]

Agree with Skins that B and C is the correct answer but my preference would be like Uriel and I would tend to do C myself.

It is correct that a max of 1/3 of the mature media of an existing filter may be used to seed a new filter but it must be remembered that the absolute amount of mature media you get out of that transfer may not be sufficient for much of a safe start for a fish-in cycle, rather it is a better seed for a fishless cycle, especially when dealing will smaller filters/tanks like this (if you think about it, as the absolute amount of transferred media gets larger, it passes the point of being able to support a fish, then two fish etc.) The other factor that makes us favor fishless is that mature media transfers don't always "take" the way we hope (the bacteria themselves may not like something about their new environment, as they are living things too.)

~~waterdrop~~

 

[Curiosity101]

I agree with both skins and wd.

I personally tend to seed with some media/filter squeezing and then spend a week fishless cycling to get the bac levels up. But 0.2 isn't that bad a level, and depending on how long the fish has been in there it may well be going down now. I'd test again in say 6 hours, if it's stayed the same or gone down then I'd follow the test by a 50% water change and then leave the fish in.

However just a note on something uriel said

Why risk you fish in your established tank by taking out to much media

It's not really a risk taking it out of the main tank... for a few reasons. The bacteria are 100% used to the conditions where there have grown. If you remove a chunk of them then it wont be long before they start replicating to make up the difference. And as they multiply exponentially it takes little to no time for them to be back to the correct amount.

 

[anon02]

I would also favour option c, at the end of cycling you will have a filter which is capable of handling a full stocking, whereas with a fish in cycle the bacteria will grow in accordance with the relatively tiny amount of ammonia produced by the fish, so your filter will be playing catch up with every subsequent stocking.
There is a school of thought that a bacterial colony that dies back leaves behind certain compounds that are readily re populated when more ammonia becomes available and that this re population happens much more quickly than would be the case with virgin media

 

[MHunt]

I think B should be fine, just keep doing the water tests and water changes when you see any Ammonia or Nitrite. You'll only prolong the job by putting everything else back. All you're having is a mini cycle, regular water changes till the tests come back negative and you should be fine.