# How does Open bottom tank work?



## Pinto (Mar 22, 2008)

Anyone has seen,heard, or have a open bottom tank.
I just don't get how it works, for example how water is against gravity in a open bottom tank.
I am curious and confuse, also it looks cool and i thinking about getting one.
Also if you have any cheap sites for those tanks feel free to post where.


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## goalcreas (Nov 20, 2006)

??
Never heard of it, explain more


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## Pinto (Mar 22, 2008)

lol, i don't know and want to learn more about it.
Watch those and i don't know the answer.


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## Zapins (Jul 28, 2004)

Looks like they are just using suction to keep the water in the tank. Basically they turn the tank upside down in a larger container, fill the tank and the container completely with water and then push the tank up to the surface. The tank's rim must be under the surface of the water in the larger container. When the tank is near the surface just put supports under the rim to keep it just beneath the surface (thick black lines on the right).


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## Diana K (Dec 20, 2007)

In addition to Zapin's sketch there will be a way to remove air from the inside of the inverted tank.


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## daryn (Jul 25, 2008)

The second clip shows the upside down tank with a airstone, if it was sealed it would cause the water level to drop till the top tank is empty. Ignore this.


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## TAB (Feb 7, 2009)

I'll stick to a "box" thank you.


A small hole hooked up to a vac pump would be a great way to remove the air. It would also be a way to fill it, but you would need a strong pump to do that.


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## Zapins (Jul 28, 2004)

You don't need a pump. If you want to see the concept at work on a smaller scale before setting up a fishtank:

Just take a drinking glass and a large bucket of water and submerse the cup in the bucket (or sink), then turn it upside down and lift it out the water so the open end of the cup is still underwater. 

The cup keeps the suction and won't let the water out as long as the lip of the cup doesn't leave the water.


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## TAB (Feb 7, 2009)

I was actually recalling a fish arch product from about 10 years ago that used a pump. I know the lowering method works. not enough "wow" for me to deal with that.


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## studdedsham (Oct 2, 2007)

You know, I just saw that fish arch last week. After reading this tread I now understand what it's for.


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## Patchworks (Dec 20, 2008)

daryn said:


> The second clip shows the upside down tank with a airstone, if it was sealed it would cause the water level to drop till the top tank is empty. Ignore this.


I'm thinking the pump if pulling air from inside the upside down tank. That way the air volume never increases!!

g


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## studdedsham (Oct 2, 2007)

That sounds like it may work as long as they are set at the same rate.


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## ripcurl711711 (Mar 9, 2010)

The water part is correct. The only additional thing about the air circulation is it's a closed system. Meaning there was an "X" amount of air left in the top after raising the inner tank. Two tubes (inlet and outlet) are connected to an air pump. The inpet is ran up to the top of the inside inner tank to suck in air, and the outlet tube is near the bottom of the tank to release air and presto! This would ensure you always have he same rate of air going in and out.:flame:

Oh, and I guess if you are actually wanting the bubbles to serve their actual purpose, oxygenating the water, you would have to "change" the air every now and then. LOL.


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## jschall (Apr 13, 2009)

ripcurl711711 said:


> The water part is correct. The only additional thing about the air circulation is it's a closed system. Meaning there was an "X" amount of air left in the top after raising the inner tank. Two tubes (inlet and outlet) are connected to an air pump. The inpet is ran up to the top of the inside inner tank to suck in air, and the outlet tube is near the bottom of the tank to release air and presto! This would ensure you always have he same rate of air going in and out.:flame:
> 
> Oh, and I guess if you are actually wanting the bubbles to serve their actual purpose, oxygenating the water, you would have to "change" the air every now and then. LOL.


So now I have to do water changes AND air changes? Maaaaaan.


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