Open Bottom Fish Tank

[fish eyes]

Hi all

Has any one seen or got a open bottom fish tank ? I have seen them on you tube and they look great. Dose any one know if you can buy them from a retailer or are they all DIY.


Thanks

 

[chrisbassist]

what do you mean by open bottom? since if the bottom of the tank was actually open all the water would be on the floor...

I've not heard of them, have you got any links?

 

[bae1994]

its not really open bottom if you search youtube open botom tank youl see them

 

[Truck]

It's a normal tank, with a tank inside with no bottom, it's a pointless bag of <insert interchangeable word here>

What's wrong with a normal tank, it's more attractive and doesn't cost a bomb, and if the pump fails you're not going to have a wet floor!

 

[chrisbassist]

yeah, just had a look, and the physics are pretty simple. but yeah, a power cut would automatically mean a flood when the pump drawing water up fails.

alternatively, no pump and a sealed top, but then getting it full would be a pain, and then you would have no water circulation there, so harmful stuff would build up...

did a quick google search for open bottom fish tank and a few things came up with how to make them and stuff (although didn't check them out) so if you really want to make one, the info is out there, but on the other hand, they have such huge design flaws i can't see the point.

 

[IAmATeaf]

Would a power failure result in the top tank emptying? From what I understand I don't think so as the top tank is filled by sucking out the air which results in the water filling the space left by air that's been sucked out. Once the top tank has water in it then it's gravity acting on the water in the bottom tank that would keep the top tank filled with water.

So in the setup in the youtube vid there must something sucking air out at the same rate as the air being bubbled in, if there was a power failure then both of these would stop working so the water would still remain in the top tank.

Wouldn't it? Or am I being superbly stupid?

 

[chrisbassist]

the pump sucking the air out at the top would stop working, allowing the pump to let air back in, unless you get a stupidly expensive pump, when air can get back in the water will flood out the bottom.

think about it like a straw, you suck the air out and the drink comes up, now if you put your finger over the top so no air can get in, the drink will stay at that height in the straw, as soon as you take your finger off letting air in, the drink will drop down the straw filling the cup with the extra drink.

i suppose there are ways of getting round the issue though, with one way valves, and such. if you really want to do it, then go ahead, but before you do, just imagine trying to clean in it, or trying to scape it. just think of the practicalities first.

 

[OldMan47]

Most of the ones I have seen had a sealed top or a recirculating pump pumping the air from the top bubble into an air stone at the bottom. Once you got them set up you would simply draw the air out once and it would hold the water up like a barometer holds up the mercury column. You extend a piece of tubing into the top of the tank from the outside and pump out the air, then remove the external tubing and voila. The tank will slowly accumulate some traces of air that come out of solution from the water. You only set up a tank like this as a demo so it is not a big deal if the water level drops inside the inverted tank over a week or two. Once you have gotten past all the "how do they do that?" comments and everyone has gone home, you simply inset the tube to allow air back into the system. If you look closely at the arrangements, the tub around the bottom has enough volume to prevent an overflow if you let the inverted tank drain completely.

 

[fish eyes]

Thanks for the info. I think i will just stick to the conventional type of tank.Less mess if any thing goes wrong.