How Long Can I Leave A Cycled Filter Without Fish?

[Katch]

I have a 29 Litre breeding tank with a Eheim 2011 canister filter stuffed full of sponge and ceramics. It is fully cycled and I always have perfect stats.

I currently have 8 Celestial Pearl Danios in there but it is almost time to take them out and cross fingers for 5 days while I wait to see if I get any fry.

How long can I leave the tank without fish between breeding attempts without loosing my bacteria colonies?

 

[Timmy_Bee]

i guess it depends on your colony, but they will start to die off in 24-48 hours (i think - i have no proof or personal experience)

You could always keep it topped up with ammonia or a bit of flake food?

I would do an ammonia test on your tank to see how much your current fish produce, and dose that ammount with bottled ammonia when its empty.

 

[anon02]

If you work on 1 inch per gallon, 8 cpd are about an optimum stocking so I would dose 5ppm ammonia per day to keep things ticking over

 

[ZoddyZod]

If you work on 1 inch per gallon, 8 cpd are about an optimum stocking so I would dose 5ppm ammonia per day to keep things ticking over

are you stating that 8 cpd will produce 5ppm of ammonia within 29litres every 24hrs? How have you worked that out?

 

[Katch]

If you work on 1 inch per gallon, 8 cpd are about an optimum stocking so I would dose 5ppm ammonia per day to keep things ticking over

are you stating that 8 cpd will produce 5ppm of ammonia within 29litres every 24hrs? How have you worked that out?

Yeah that's ridiculous - no fully stocked tank or overstocked tank is going to be producing 5ppm a day - we only use 5ppm during cycling to give the bacteria as much of a headstart as possible before adding fish.

I'm not sure that adding ammonia is the answer - given that in those 5 days I am expecting eggs to be hatching I don't want to be exposing them and fry to free concentrations of ammonia.

 

[waterdrop]

Oh, so its not an -empty- tank, its a tank with EGGS in it! Interesting question! WD

 

[anon02]

How much ammonia is produced in an optimally stocked tank ? If there are eggs and they do hatch, how much ammonia will your filter have to cope with If your filter is working as it should you will never know. I was going off cycling figures seeing as they are the only figures available

 

[roadmaster]

I will assume that you were feeding the Celestial pearl Danios while they were in the tank. Were it me, (and it ain't), I might feed one third of what I was offering the fish once every other day ,or every two days. This will prevent bacteria from dying completely, although some no doubt will, due to decrease in food available.
Bacteria can increase rather quickly in the aquarium assuming conditions are favorable and I would not be too worried about the amount lost but would NOT increase the bio-load on such a filter too much at once.
A handful of Trumpet snails is what I use in quarantine tank when not in use and I feed them sparingly. Keeps the bacteria in the filter active, and I seldom place more than a few fish at one time in the tank.
Should I purchase a small school of fish,, I simply plan on daily small water changes for the duration the fish are in quarantine.

 

[fluttermoth]

The only way is to move the filter and run it in another tank to keep the bacteria alive and put it back in when/if you have fry. That's what I've always done
You certainly don't want to be putting ammonia in there with eggs.

 

[the biffster]

i have done something
like this in the past
i used to feed the filter with
a small amount of flake food
just to keep it ticking
over mind you do have to test
your tank regular keep an eye
on your ammonia and nitrates

 

[Tolak]

You'll lose 10%-12% every 24 hours. With the minimal amount of waste that fry produce this shouldn't be an issue over 5 days.

 

[Katch]

So with no ammonia and nitrite being produced we'd be looking at a complete death of the filter within 10 days.

 

[roadmaster]

So with no ammonia and nitrite being produced we'd be looking at a complete death of the filter within 10 days.

I don't think it would take that long but then again, I've not wished to expieriment.

 

[OldMan47]

10% per day will take much longer than 10 days Katch. Day 2 you start with 90% and lose 10 % of that, call it 9%. Day 3 you start with 81% and lose 10% of that, call it 8% of the original, day 3 you start with 73% of the original, etc.

 

[Tolak]

From my experiences a mature filter, one that has been running for several months if not years, the nitrifying bacteria seem to go dormant more than completely dying off. A mature colony of nitrifying bacteria is capable of doubling every 24 hours, and as OM47 stated, it will take quite a bit longer than 10 days for the colony to be completely gone.

On many occasions I've pulled stock from a tank, left the filter running on the empty tank for a few weeks, and stocked the tank after a large water change. I'll do a large water change daily for a few days, and let the tank run after that with nothing more than the regular maintenance.