Fish Tank Open Bottom - How is it done?

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I am facinated by the video at
and wondering how the effect has been achieved. It would be brilliant if I could get a similar effect on my 8' tank.

Nature dictates that gravity will win, but this setup seems to defy the rules.

How can you maintain water in a tank this way unless you can keep a vacuum in the tank?
How can you maintain a vacuum in the tank with an airstream running?
Does anyone know who owns this setup?

I have to know! It has got to be the ultimate in unusual setups!
 

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definately cool! it looks like a tank inverted over another tank. what i'm not sure about is if it was kept that way or changed later. not sure how you can have the air pumping in the upper tank without pushing water into the lower tank after a long time.

but definitely cool! now I want one!
 

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Awsum The way I see it is the inverted tank for the water to stay but the air you put in has to be removed to keep the water level up. He would need a air line running up into a air camber sump at the top. Draw air out at the top and bubble it back in at the bottom.
 
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I have checked all the videos I can find on this setup, and the guy comes from singapore and has several layouts by the look of it. From what I can gather, there is something on the lhs top of the tank, which I suspect is a vacuum pump. Quite how it's regulated or how powerful it would need to be I haven't worked out yet, but I will!

The tank itself appears to sit on the floor of the lower tank, with one side cutaway to just below water level.There must be a glass shelf on the full side too, to allow for the decor. I think I'll have to work out the power needed to hold that sortof volume of water up, and then all I haveto do is find apump strong enough to do the job! Happy days!
 

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On the 3rd page of posts he says he uses a submersible box filter. No mention of what size or anything, but I'm wondering if he's using one made for a pond to get the kind of flow needed. Nice look though.
 
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The submersible filter he is referring to is the large one to the left with the water cascade, but I can find no connection with the top tank from there. I can duplicate the effect easily by inverting a tank, but still have to work out the system to hold the water in place.

What I envisage is a one-way valve hooked to a vacuum pump, but they are usually noisy, and can't imagine anyone wanting something like that running in their living room! The weight of water is dependant on the size of the top tank, but it would have to be pretty substancial to hold that much water in place. I'm having a word with an engineering friend of mine who may be able to come up with a few ideas.

I'll let you know the result.

Simplicity is the best way!

I just tested a theory I had, using an old whisper air pump and a spare 10 gallon tank. Here's what I did:

The pump:
I connected a small bore tube to the air intake of the whisper. (Luckily, the one I have has a rubber base with a single air intake hole.)
I sealed the pump with silicone, all round the mains cable and air outlet nozzles as well, so that the air only had one way in.

The air intake was then connected to a length of 6mm air tubing, with a check valve inline, long enough to go from the pump to the bottom of the tank. Another piece of small bore pipe was then pushed into a suction cup and the tube attached. This was then placed as close to the bottom of the tank as I could get it.
I connected the two pump outlets together with a tee piece. These were left un-connected to anything, to vent the air outside the assembly.

I turned the tank upside down and rested it on the top of my 4' tank, resting it on the stress bars.
When this was complete, I connect my hose pipe to the shower, so as to get the temperature right and carefully added water to the tank until it covered the bottom lip of the up-turned tank.

Then I connected the pump to the mains and waited.
Very quickly the water level started to rise in the tank. I had to keep topping the water up in the tank to make sure the lip stayed under the water. It was amazing! Within ten minutes the whisper had drawn the water to within two inches of the top of the tank. I put an airstone on the outlet and put it under the rim, so the air went back into the tank rather than escaping, and the water level stayed where it was!

I have been looking in the wrong direction! It's not the weight of water that is the problem, it's how to extract the air from the top. The water is supported from below by the rest of the water in the bottom tank, and it takes very little suction to get the column up the tank! It is also near impossible for the bottom tank to overflow, even though there is 10 gallons more in it, as if the water level drops below the lip of the top tank, a large air bubble shoots in and the water displacement restores the level to seal again!

I like it, and so do the fish! They have already started going up there.

Here's the proof:
 
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It needs a good pump though, my whisper has already sprung a leak, but I've re-sealed it tonight and it should be ready to go again in the morning. Check valves are essential folks! (If the air gets into the vacuum side, you won't have long to stop the flow!)

I was right about the lack of overflow too. When I drained it down tonight, I had no problems, apart from the danio that decided to go down the tube!...lol (Good job I was draining into a bucket!) He was returned to the tank unharmed. The air getting into the tank is quite violent though, so I think it would be worth bleeding the tank down gently, rather than letting the air force it's way in. I managed to do this by disconnecting the vacuum side above the check valve. A tap here would be useful. When I set this up over the 8' I'll buy a new pump (The other half has already agreed to that!) specially for the purpose and drill holes in the glass so that I can fit connectors directly to where I need them, to cut down on the tubing required and make the job tidier.

Tomorrow's test should get most of the kinks out, hopefully without soaking the carpet!
 
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Ok folks, the second run was much more successful thean the first one, and I didn't spill a drop!

The method works really well, and now I can get to making the larger version for the 8' tank. Funny thing is, that when I took the tank down the other night, all the fish were looking for it! I guess I shall have to leave it there now!
 
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Thanks ATMMachine, that's just the info I need. I can get one ordered straight away, should have it by next week, in time to try it out on the new tank I'm gonna be building over the weekend. It'll cost me a bit more than if I ordered it from Boss, but haven't got delivery to cover then.
 

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Cool, I love mine, it's much quieter than the whisper, only thing I've done to it in almost two years is tighten the screws to keep the body parts of it from rattling, though I find it sits better on a cloth or pillow than a hard surface.
 
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made a couple of small mods to the setup over the last couple of days, which has made it more stable.

The first was to drill a hole in the top to take the vacuum pipe and the second was to put a baffle in the top of the tank to stop the water vapour from getting into the pump. This had to be done, since the other night, my pump burned out when the water shorted out the coil!)

A new pump and the mods in place, it's running perfectly now. Checked the circulation in there yesterday and moved the air stream to one side of the tank to ensure that the water circulated out of the top and into the bottom tank. This is fine now and the water is continuously circulating around the entire system, not just the top tank.

The fish are really loving the extra room, and are swimming in and out of it quite happily.

Now I'm sure it'll work, I went to the glaziers this morning and ordered the glass to make a larger, more permanent top for it. It will measure 24"x24"x11" with an entry flute to come inside the stress bars and be supported properly. this will enable me to lower the water level in the bottom tank to a sensible level below the bars, rather than half an inch from the top rim!

Anyone else trying this yet? lol!

For those of you following this project, I have now constructed the full-sized tank and will be leak testing it over the weekend. below are some pics of the construction to the finished build.
 
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Silicon cures much quicker than it used to! The tank is now undergoing leak testing already! I have set it up in the bath and filled it the way it's going to be used, the right way up. When I thought about testing, it occurred to me that normal water testing wouldn't give me the right pressures on the seams, since this tank doesn't have to support the weight of the water the way normal tanks do, so the pump and bath worked well.

here are some pics of the tank under test:

Disaster!

I knew it was going too well! Got everything ready, painted the back of the tank, and left it in the sun to dry.

NEVER LEAVE A TANK IN THE SUN WHEN YOU PAINT IT!!!!!!!

the back panel which I painted got hot, while the front panel didn't. Now it's a cracked tank! there was a tiny flaw where the glazier cut the corners, and it ran from there. (it's strange, but in all the time I worked with windows and glazing, I never drilled the glass to cut an internal corner. This glazier insisted that this was the only way to do it, and that is what caused the weakness.)

Oh well, we all make mistakes, and this was a big one. Now it's back to square one, ordering the glass all over again. once these things are siliconed, there is no way to get them apart again, so the whole thing is ready for the bin.

Lessons learned:

Paint the back panel BEFORE assembling
Never put the tank in the sun with paint on any of the panels
Double check the cutting for weaknesses
Maybe cut the glass myself. (No-one else to blame then!)

Tomorrow I start again. I suppose it's better that it went while it was empty, not full. Would have made a terrible mess on the carpet! Lol.

ok, attempt two:

managed to save most of the glass from the original tank, so just had to replace the front and top panels, along with some re-designed pieces of glass.
Cut the front panel square, and designed a new flute. This was made up and joined to the front with an overlapping piece of glass. Doesn't look so good, but is stronger.
Also put in a stress bar across the front panel, just above the neck of the flute, to add more strength.

Stuck everything together and left overnight to cure.
Next morning, set it up in the bath again to leak test. Found a leak. drained it down again and let it dry, and then sealed the leak. Another night of curing.
back into the bath again, another leak test. This time it worked perfectly and filled to 1 inch from the top without any problem.

left it there all day and night, just to be sure. All well, water level stayed exactly where I left it.

made the stand and fitted it over the 4' tank, ensuring that it was strong enough to supplort the weight. No problem there.

Drained the tank down, rinsed it out and put it onto the stand. Great, the flute was perfect, fitted the stand well and all looked good.

started to fill it up. watched it constantly to make sure that nothing untoward happened. got the tank halfway filled and then heard a strange noise. stopped the fill and checked all round. couldn't see anything wrong until my partner noticed the shelf was out of line. it had dropped by 6mm on one end!

The added weight of water had overstressed my shelf, causing the joint to move. Oops!

Third time lucky, so they say! I have repaired the crack in the bottom panel, and am waiting for the silicon again. Will leak test again tomorrow!

Here it is! The finished, (well, apart from the light canopy), setup!

After several repairs and a lot of swearing, it finally came together and worked. Here are the pictures:
 

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