Does a Quarantine Tank Need to Be Cycled?

[OfficialThomas]

Hi! I have never quarantined my fish (and never had problems) but I want to start quarantining new fish from now on.

I was wondering if you need the quarantine tank to be cycled. I saw the video Irene made on the aquarium coop channel about using a sponge filter but I use a hang on back filter in my display tank and I don't want to add a sponge filter.

Does a quarantine tank need to be cycled?

Could I use a filter intake sponge instead?

Thanks!

[AllFishNoBrakes]

I think it’s definitely in your best interest to cycle your quarantine tank and then keep it cycled. I have (3) 10 gallon quarantine/hospital/grow out tanks and keep them cycled at all times. 
 

I’m not sure how a filter intake sponge would replace a filter? I run small sponge filters in all 3 of the tanks mentioned above 

[mynameisnobody]

Yes it definitely needs to be cycled. 

[Guppysnail]

If you mean placing the seasoned cycled sponge intake prefilter from an established tank on a hob in your quarantine tank instead of using an air driven sponge yes it will work the same. As long as water is circulating through it. 
Alternative is cut a hole in the bottom of the prefilter and slide that over the plastic cage for an air driven sponge. 
it is preferable to fully cycle a Qt but just using established filter media is acceptable. 
Note it will not be as stable and may still show spikes just not as drastically so will need tested daily and water changes done as needed. 

Edited December 19, 2022 by Guppysnail

[rockfisher]

Are planning on leaving your quarantine tank up. If so set it up before hand and cycle like you would any other tank. I think this is the best way. If not used a intake sponge from the hob you are running but if there is issues with that tank you don’t want to do that. I would set it up and leave it up even if it not big and out of the way. Mine in a corner in the garage 10 gal and has a sponge filter with a usb air pump. I have 3 female guppies so the tank stays in order and that’s that. For me I don’t quarantine all my fish that are new but I have many tanks and to be totally honest if the fish are not going in one of the breeding tanks and are not of monetary value/ rarity I have not quarantine. Most of may fish are quarantine and most treated for worms if I have not dealt with the seller be fore.

[Patrick_G]

I have a few extra sponge filters hiding in my 75 gal display tank. I also remove the intake sponge from that tank’s hang on back to seed a small hang on back that I use for quarantine or hospital tanks. 

[Flumpweesel]

It's not always possible to have a fully cycled quarantine tank on standby so Irene's video on how to set one up as needed is great.

Using cycled media is really helpful and can save you some work but as long as you keep a close eye on the water parameters and feed very lightly you should be able to get through the period with water changes.  I have a cave I move out of the main tank when ever I need to and if I'm organised I start running a small internal power filter in an established tank for a week before I go shopping 

[DaniV]

I'm in the process of my very first quarantine.  I went and got a sponge filter from ACO and had it in my cycled display tank for a few weeks just to start getting that nice beneficial bacteria, in the meantime I was buying my quarantining materials little by little.  By the time I had everything set up, I took out that sponge filter and placed it in the quarantine tub to give the cycle a kickstart.

Did it prevent any raising of ammonia and nitrites completely for the quarantine cycle?  No, but it definitely helped keep those numbers low and manageable compared to when I was cycling the display tank.  I've been adding live bacteria and some Seachem Prime just to be safe, and I've got about 2 more weeks left on my quarantine.  Process seems to be working!

[OnlyGenusCaps]

On 12/18/2022 at 9:07 PM, OfficialThomas said:

Does a quarantine tank need to be cycled?

Hot take: No, you do not.  I've done it.  It's not my preferred method, but sometimes life is does not follow a plan.  I am sure there are species that would not tolerate it, but when I have done it, I have done 25% water changes 2x daily.  Ammonia stayed in safe ranges, as did the rest of the measured baddies. Maybe don't try it with a prize discus, but it can be if you need to.  But it sounds like you are planning, so...

On 12/18/2022 at 9:07 PM, OfficialThomas said:

Could I use a filter intake sponge instead?

Yes, I agree with @Guppysnail.  If you are using an intake sponge on a HOB, and have a similar HOB on the QT, swapping just the intake sponge should be enough to take care of your biofiltration needs.  Indeed my QT tank is prepped similarly.  I have a single 20H tank that I use for QT, wither it be freshwater, saltwater, or dart frogs.  For the fish, I use a Seachem Tidal HOB (my only one) and have sponge hidden in other tanks (behind matten filters, or in sumps) cut to the proper size for the HOB.  When I need a freshwater QT, I put in the proper water, and add the correct pre-cycled sponge.  I've dumped in upwards of a dozen fish, and the water quality stays great!  Remember though that the longer the sponge is cycled, the better your results will be.  Also, keep in mind that though you can use any SW cycled media on any other (ocean is pretty much all the same water type), don't try to use a soft, blackwater tank sponge on a hardwater QT or vice versa.  Your results will be disappointing. 

[Chick-In-Of-TheSea]

Bottled bacteria is a nice option if it's an emergency setup. 

How do you guys keep your QT tanks cycled after the last fish has vacated?  I empty/disinfect mine and then I put the sponge filter back into an established tank and just leave it there.  Prime Time leaves snails in his QT tanks when there are no fish in them, and he feeds the snails, and that keeps his tanks cycled.

[gardenman]

As is often the case, it depends. If your quarantine tank will hold one neon tetra and you're changing water regularly and have plants, then no, it probably doesn't need to be cycled. The waste output from a single smallish fish would be so insignificant that the plants and whatever bacteria happened to be around should handle it fine combined with the water changes. If you're filling a ten-gallon quarantine tank with enough fish to crowd a fifty-five-gallon tank then no matter how well cycled it was, it's unlikely to be able to handle the bioload. 

Pretty much everything in the aquarium hobby is a balancing act. Bacteria grow relative to the amount of places for them to inhabit and the food available. Lots of places for bacteria to live with lots of food gets you lots of bacteria. A sterile, barren wasteland of an aquarium gets you few, if any bacteria. Sponges give bacteria lots of places to live, so that's why so many fish keepers use sponges. A bacteria laden sponge dropped into a barren tank with no food source will have the bacteria starving and dying off in short order. Gradual changes in bioload work well. 

My tanks are all grossly overstocked but that's because the fish reproduced in the tanks, and the bacteria were able to keep pace with the fish. If I were to remove 95% of the fish, there could be an ammonia spike as much of the bacteria would starve and die off. If the surviving bacteria weren't able to keep up with that sudden die-off, the ammonia would spike despite an apparent lower bioload. If I gradually reduced the bioload, the bacteria would adjust with the reduced bioload, and all would be well. Such is the life of a fish keeper. It's all about balance and stability. 

By their very nature most quarantine tanks will experience instability and become unbalanced. Unless you keep an identical bioload in the quarantine tank when you're not quarantining fish and then when you are, there will be swings. Even the meds used in a quarantine tank can affect the cycle (if there is a cycle). In a perfect world, you'd want a very large, stable quarantine tank. That would add a ton to the cost of meds and make it harder to spot issues though. Just do what you feel is best and learn from your experience. If you need to quarantine a fish and you don't have a cycled tank ready to go, toss it into the quarantine tank and keep an eye on it. If the ammonia spikes, change water. If all's good, then kudos.

[Bev C]

i when started a quarantine tank I cycled it like regular  new tank  with real plants i used fish food and fertilizer for the ammonia    source for the cycle instead of using fish it took a while to  cycle but worth it

 i keep mine running 24/7  it has plants and a few  mystery snail babies in it full time if i need to quarantine a fish  or snail i just move  my  quarantine snails to a different tank till the tank is clear to move them back  ,, anf i use it for my aquarium experiments to  but i also keep a rubbermaid tote  handy for emergencies leaks and a extra sponge filter in my main tank you never know when you will need it to start a tank or need a new sponge in a hurry  when i use medicine i replace  the sponges with a already season sponge 

Edited December 21, 2022 by Bev C

[AllFishNoBrakes]

On 12/20/2022 at 6:54 AM, Chick-In-Of-TheSea said:

How do you guys keep your QT tanks cycled after the last fish has vacated?

Snails, or other fish. Sometimes I’ll move some of my Platy’s over, or when my newest batch of fry is ready for a bigger tank the quarantine tank becomes a grow out tank. It all keeps the cycle going and ready for whatever is coming next!

[Cinnebuns]

I'm sorry I didn't read all the comments so I apologize if this was covered. 

One of the best tips I ever got was to run a smaller filter in your main tank. This will keep a filter cycled for when you need to setup a quarantine tank or any other emergencies. I personally like the tetra whisper internal filters for this. They fit a small tank well. You can also do this with a HOB filter or really any filter.