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Can You Cycle a Fish Tank With Water From Another Tank? (Answered)

I know cycling a fish tank can take a lot of time. Fortunately, there are a few ways to cycle your fish tank instantly.

But is using water from another cycle tank one of them?

You cannot cycle a fish tank with water from another tank. The beneficial bacteria don’t live in the water of a cycled aquarium. However, you can use filter media from another cycled aquarium to cycle a new fish tank.

Though you cannot cycle your new fish tank with the water of a cycled aquarium there are some other ways to cycle your fish tank instantly.  I’m going to cover them later in the article.

Can You Cycle a Fish Tank With Water From Another Tank? image

Why you cannot cycle a fish tank with water from another tank?

Betta fish image with text "why not" and question mark

The reason you cannot cycle a fish tank with water from another tank is the beneficial bacteria doesn’t live in the water column or at least a lot of beneficial bacteria doesn’t leave in the water column of a cycled aquarium.

So if you add the water from a cycled aquarium in your fish tank then it will contain very few beneficial bacteria which will not be sufficient to cycle your fish tank.

Besides, nitrate lives in the water column of a cycled aquarium. So when you add water from a cycled aquarium in your new fish tank, you will also add a lot of nitrates to your fish tank.

How Long Does It Take To Cycle A Fish Tank? (Without And With Fish)

Where do the beneficial bacteria live?

The beneficial bacteria live on all surfaces in a cycled aquarium.

The beneficial bacteria can be found on the surfaces of the following things in a cycled aquarium:

  • The inner glass walls of a cycled aquarium
  • On the surface of the substrate of a cycled aquarium
  • On the surface of the ornaments like driftwood or rock, etc
  • On The leaves and stem of live aquarium plants
  • In the filter, specifically, the filter media contains a lot of beneficial bacteria.

What Happens if You Don’t Cycle a Fish Tank? (Is It Really Necessary)

How to cycle a fish tank using another tank?

fish tank image with text "HOW TO CYCLE WITH A CYCLED TANK" and question mark

If you have a cycled aquarium or if you have access to a cycled aquarium say, your friend has a cycled aquarium then you can use that aquarium to cycle your new fish tank.

Actually, there are a few ways to go about it.

1. Add filter for filter media from the cycled aquarium

The filter of a cycled aquarium, specifically, the filter media of a cycled aquarium contains a lot of beneficial bacteria.

So if you can add the filter or filter media from a cycled aquarium in your new tank then you can jump-start the nitrogen cycle in your new tank.

If you cannot add the filter or filter media from the cycled aquarium then you can put a new filter in the cycled aquarium and keep it running for a couple of weeks.

In a couple of weeks, the new filter will have sufficient beneficial bacteria to jump-start the nitrogen cycle in your new fish tank.

If you are going to add a new filter in the cycled aquarium then I recommend you add a sponge filter.

Because sponge filter has sponge which provides a lot of surface area for the beneficial bacteria to form their colonies.

Besides, sponge filters are very cheap.

Check the price of this sponge filter at Amazon here

2. Add gravel from a cycled aquarium in your new tank

If the cycled aquarium you have access to has gravel as a substrate then you can simply pull out some of the gravel from the cycled aquarium and put it in your new fish tank.

As the surface of the gravel of cycled aquarium has a lot of beneficial bacteria, it will jump-start the nitrogen cycle in your new fish tank.

Either can spread out the gravel substrate from the cycled aquarium in your new fish tank. Or you can put the gravel from the cycled aquarium in a mesh bag and hang the mesh bag in your new aquarium. This will seed beneficial bacteria in your new fish tank.

Besides, if the cycled aquarium has a ceramic ornament then the surface of the ornament will also have a lot of beneficial bacteria deposited on it.

So, if you put the ornament in your new fish tank then it will seed your new fish tank and jump-start the nitrogen cycle.

How Do I Know When My Tank Has Cycled?

How to get the live beneficial bacteria if you don’t have a cycled aquarium?

fish tank image with beneficial bacteria bottle

If you don’t have a cycled aquarium then you can borrow filter media or gravel from a few sources.

1. Local fish store

Your local fish store will have a lot of cycled aquariums. So if you ask them to give you a filter media or gravel from one of their cycled aquariums then they will most likely give it to you.

2. Ask your friend

If any of your friends have a cycled aquarium then you can ask him or her to give you the filter media or gravel from his/her established tank.

3. Local fish club

If there is any local fish club in your area then these clubs have a lot of experienced aquarists or fishkeepers. If you ask them, they can give you a filter media or gravel from their established tank.

5 Things to keep in mind while cycling a fish tank with another tank

fish tank with a fish and text "cycling mistakes"

Cycling a new tank using an already cycled aquarium is a very reliable way of cycling a new tank.

But there are a few things that you should keep in mind while cycling a fish tank using another tank. Or else, your fish tank cycle will never complete. Worst, you may introduce harmful bacteria and viruses in your fish tank that can cause disease to your fish.

1. Keep the new fish tank up and running

Before adding anything i.e. a filter or filter media or ceramic ornament or gravel from a cycled aquarium in your new fish tank, the new fish tank should be up and running for at least one day.

This is important because when you keep the new tank running for at least a day the water chemistry in the new tank will be stabilized.

This will help the beneficial bacteria when you add it to the new tank.

2. The beneficial bacteria need water to survive

When you carry the filter or filter media or gravel from a cycled aquarium in your new fish tank to seed your new fish tank, make sure to keep the filter or filter media or gravel wet with the water from the cycled aquarium.

This is important because the beneficial bacteria deposited on those things need Oxygen and they get the dissolved oxygen from the water.

So, you should carry the filter or filter media or gravel in a polybag containing water from the cycled aquarium.

3. Transfer the beneficial bacteria within one hour in your new fish tank

As I have mentioned earlier, you should keep the filter or filter media or gravel from the cycled aquarium wet with water from the cycled aquarium and carry it with the water from the cycled aquarium. You should also make sure to add the filter or filter media or gravel in your new fish tank within one hour of pulling it out of the cycled aquarium.

This is important because the beneficial bacteria need dissolved oxygen to survive. And the water in the bag in which you will carry the beneficial bacteria will have limited dissolved oxygen which may last a maximum of one hour.

4. Keep the temperature of your fish tank above 65° F (18° C)

The ideal temperature range for the beneficial bacteria is between 65° F to 85° F (18° C to 29° C).

If the temperature of the water of your fish tank is below 65° F (18° C) then the beneficial bacteria will not grow in your fish tank.

That’s why before adding the beneficial bacteria through a filter or filter media or gravel of a cycled aquarium, you should make sure that the temperature of the water in your fish tank is above 65° F (18° C).

You can easily maintain the temperature of your fish tank in the ideal range i.e. 65° F to 85° F (18° C to 29° C) using an aquarium heater.

And you can also easily check the temperature of the water of your aquarium using an aquarium thermometer.

If you don’t already have a heater and thermometer then I recommend Orlushy Submersible Aquarium Heater.

It comes with a thermometer so you don’t have to buy the thermometer separately.

You can check its latest prices and reviews at Amazon here.

5. Get the live beneficial bacteria from a trusted source

When you add the live beneficial bacteria in your fish tank by adding a filter or filter media or gravel from another tank then if another tank contains harmful bacteria and viruses you may also introduce them in your fish tank.

That’s why you must get the live beneficial bacteria only from a trusted source.

Conclusion

The beneficial bacteria don’t live in the water column of a cycled aquarium.

That’s why you cannot cycle a fish tank with water from another tank.

However, you can cycle your new fish tank by adding filter media or gravel from a cycled aquarium in your new tank.

Just keep in mind the things I have mentioned in the article while you get the filter media or gravel from a cycled aquarium.

Else, your fish tank may not get cycled. Worst, you may introduce harmful bacteria and viruses in your new fish tank.

I hope you found this article helpful.

If you do, please share the article with anybody who can benefit from the information.

Happy fish taping!

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