3 years ago #1

how long does it take for a fresh water fish tank to cycle?

3 years ago #2
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Generally it takes 4-6 weeks and sometimes more than that depending opon tank size,type of cycling practiced,temp,water changes etc

3 years ago #3
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It also depends if you cycling with or without fish in the tank. Smaller tanks can get fully cycled in 3-4 weeks, bigger as it was said already up to 6 weeks usually.

2 years ago #4

What size is considered "bigger"? 20 gallons ?, 55? 100?

2 years ago #5
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I guess its a matter of opinion. I consider 'smaller' tanks to be 20-30g and under, generally. 'Bigger' is 55g+ up pond size (1000's gallons). Others may differ in opinion.

2 years ago #6
Fresh Member
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Hi There,

It's all depending on your size tank as an example, a 5 Gallon (21 Liters) will take about 1,2,3 weeks depends, there are many different way to cycle. You can cycle with Pure Ammonia (- Generally From Hardware Stores)shake it if its bubbly or foamy DO NOT use it that's how you can tell if it Pure if it doesn't foam or bubble your fine!)

You can also cycle with fish flakes, put some fish flakes in Every other day (-Once every 2-3 days)


its better to have Live Plants in your Fish Tank
Make sure you have an API Fresh Water Test Kit, (- That testes for Ammonia, Nitrite, Nitrate, and pH
Be sure to do water changes with Gravel Cleaner

Also be sure to read up on the Nitrogen Cycle for Fish Tanks useful Link: AQUARIUM WIKI(JUST LIKE WIKIPEDIA)http://www.theaquariumwiki.com/Main_Page

AQUARIUM WIKI NITROGEN CYCLE http://www.theaquariumwiki.com/The_Nitrogen_Cycle

1 year ago #7
Gold Member
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hello guys, i have a 20 gallon fish tank for 4 months now. i purchased a 75 gallon tank. i wanted to know how long would it take for my tank to get cycle if i use the filter i am using on my existing tank, its a 50 gallon filter by the way. would this minimize the cycling process, how much time would this safe me?

1 year ago #8
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Can you please post this in a new thread? This one is month's old. Just type your question in the green box at the top right and we'll be happy to help you.

We don't use old messages to type because then new messages with urgent questions get pushed to the bottom.

1 year ago #9

Ace is right, but to answer your question:

With the existing filter and existing filter media, you should see a near instant cycle. Just don't add any new fish for the first few weeks with the larger tank, and I would recommend either re-using the substrate from the old tank in the new or at least putting the old substrate in a mesh bag and putting it in the new tank to help colonize the new substrate with bacteria quicker.

If you have a sponge or floss in your filter, squeeze it out into your new aquarium water. It will be cloudy for a bit, but it will help populate the bacteria you want in the new tank.

FYI I did this when upgrading from a 10 gallon to a 37. It was an instant cycle.

11 months ago #10

Still not sure if I need to put food into the tank to help it cycle quicker as well as using some of the old stuff .

7 months ago #11

I have a 50 litre tank how long will it take

1 month ago #12

Just so you know! I have a 90 gal. & have had an- up to 90 gal. but recommended for 75 gal Filter on it for about a year! The ammonia has always been high and we lost our fish all 30-40 of them! If you intend to use the 50 gal filter on your 75 gal you'll be high risk of losing everyone in there. We bought a second filter & now things are getting better. Good luck to you!

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