Tropical Fish Forums

[romaurie]

Vacuumed aquarium instructional video.

http://www.youtube.com/watch?v=gUw42Yztlu4


This system was built in 2004 inspired by the idea of using a plastic tube filed by immersion but creating the vacuum artificially.
A number of refinements have been made and a number of set-ups based on this basic principal built.
The original system was aired on "The Fishkeers Forum " to guage interest.If you Google "The Romaurie Effect" you will see how far reaching that interest has been.
Romaurie

[katienaha]

I remember someone on this forum discussing the idea of a water bridge, and it was a lengthly thread. Was it 59 who started it? Caton??

This kind of covers that I think.
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Let the current take you where you may not always want to go.

[Caton]

Hmm, I haver never seen that before...
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[59FIFTY]

I remember it. But it was neither of us. It was maybe iansmith? I am positive it was Ian something or another.
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In the End, we will remember not the words of our enemies, but the silence of our friends. - Martin

[romaurie]

It appears the year 2004 was when this principal started getting attention.I was prompted to test the idea of applying a vacuum artificially after reading an article from Bio Elite in South Africa about using a PVC clear tube to link 2 aquariums.I thought if I applied the vacuum to the empty system the evacuated volume should pull in water.The author provided a link to a US patent issued in 1934 for this idea.
A book called "The Fish Highway" was published briefly and another US patent applied for in 2003 and issued in Feb 2005 for " An aquarium enhancement system" that employed a vacuum to fill an amazing series of drawings of very artistic aquariums.Nothing built, in fact with the knowlrdge base I have aquired building my systems some of the drawings would require a glass sculpture to put together.
I saw none of these at the time.My system was aired on The Fishkeepers Forum in March 2004.It was first utilised commercially in 2006 for an Open Bottom Aquaium in Singapore.
It is only in the last year that I have dug-up these references by extensive search.
To date the largest public system demonstrating this idea is in Oita Vietnam.They got the idea from a short clip I put on YouTube of drilling holes on the water line to pull air in by vacuum.
You really need to have one in operation to see first hand the amazing potential of the system.

[keithkyli]

Question: Water pressure in the waterbridge / open-bottom tank

I have some interest in this topic, and although I don't have the resources or the need to make one, I would like to ask some fundamental questions on behalf of the fish.

The reason why I am asking this question is that when I view clips about these systems, I notice that usually the fish only stay in one part of it, e.g. most of the fish stay only in the open-bottom tank at one time, or all of them swim only in the main tank at another instant.

I reckon that fishes sense the depth of water by water pressure, and they adjust their bladder gas to move up and down in the water column. In a normal tank or in the wild, pressure increases as depth increases. If the fish wants to physically go up, it releases more gas into its bladder to give itself a lower density than the surrounding water. It then rises until it meets water with the same density as it is.

However, in an open-bottom or waterbridge system, this simple rule seems to be challenged. I am no physics expert, I guess that the pressure in the open-bottom tank / waterbridge is the same as the level at which the water meets the main tank. For example, if the opening of a waterbridge meets the main tanks at a depth of 20cm, then the pressure in the whole waterbridge is the same as 20cm depth in the main tank.

Suppose we have a waterbridge connecting tanks A and B. If a fish wants to move from tank A to tank B through the waterbridge, it has to physically go up -> horizontal -> down. But according to the fish's senses, the whole tube has uniform water pressure. Its eyes tell it to go up, but the pressure sense tells the fish that the pressure has not changed. The fish may be scared or confused by the contradicting reports from its senses and decides not to risk. Thus we seldom see fish actually swimming freely between the waterbridge and the main tank, especially physically fragile fish. For instance, I usually see parrot cichlids but not angelfish, or cyprinid sharks but not small goldfish, swim through the invisible barrier. Or maybe it's only because of difference in decoration, I'm not sure.

Is my assumption correct? I guess a quick way to prove my hypothesis is to put a waterproof watch with depth perception function into such a system, but it would be very time-consuming and the pressure difference in a household aquarium may be too small to tell. I guess very few people have thought about this point when they build their open-bottm tanks or waterbridges. I have Googled a little, but most discussions are from the aquarist's perspective, not from the fish.
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Diamond Hill, Hong Kong

[jsuereth]

Good concern, but the water pressure will actually be less in the tunnel. the same physics apply. This is why the tunnel has to be air tight because if air is allowed to enter, then the pressure in the tunnel returns to normal and the water quickly renters the original tanks. Normally that water is at a lower pressure than would be expected of an open tank n the same position.