ctsniper86 Posted October 11, 2007 Report Share Posted October 11, 2007 Anyone ever made one of these? I can't find any designs online. Quote Link to comment Share on other sites More sharing options...
paul_r Posted October 11, 2007 Report Share Posted October 11, 2007 that doesnt look too tricky to build, logically it looks as though the bottom (pond) part would need to hold more more water than the actual tank. The top of the tank would need to be fully air tight, looks to me as if there is an air pump at the top of cabinet (inside sealed section) and is is re-useing the same oxygen over and over. otherwise eventually there would be too much air in the tank part which would force the water out. I think that would be relativly easy to make, think of playing in the bath as a kid, used to fill a jug with water put it upside down and then lift it out of the water, the water would rise with the jug until part of the jug breached the surface of the water and all the water came gushing out. Quote Link to comment Share on other sites More sharing options...
smidey Posted October 11, 2007 Report Share Posted October 11, 2007 at first i thought that the vacume would hold the water up but they have an airstone in there so it should empty.......? Quote Link to comment Share on other sites More sharing options...
Ianab Posted October 11, 2007 Report Share Posted October 11, 2007 Only tricky part would be finding a pump that would pull a decent vacumn while pumping a mix of air and water out of the upper tank. Other than that it's just 2 tanks, a normal lower one and an upside down upper with a suction fitting on the top. I would have the lower tank bigger too, in a power cut the top tank would eventually drain back to the lower one. Cheers Ian Quote Link to comment Share on other sites More sharing options...
Ianab Posted October 11, 2007 Report Share Posted October 11, 2007 at first i thought that the vacume would hold the water up but they have an airstone in there so it should empty.......? The clever part is they just keep pumping the air AND water out of the top. As long as your pump is moving more volume than the airstone puts out then the water level will stay up 8) Cheers Ian Quote Link to comment Share on other sites More sharing options...
ctsniper86 Posted October 11, 2007 Author Report Share Posted October 11, 2007 I've read thru the post on the video page and it seems he didn't reuse the air that is pumped, but some people thought he had a sort of pressure valve on the top of the top tank and that it let the air out but not in, like some one way valve. Quote Link to comment Share on other sites More sharing options...
paul_r Posted October 11, 2007 Report Share Posted October 11, 2007 i dont think there is any water pump, looks to me as if the air pump is reuseing the same air over and over. pretty simple really, the only thing to make sure of is that the upper compartment is completely leakproof, perhaps have some sort of hose attachemnt at the top for the initial fill Quote Link to comment Share on other sites More sharing options...
Ianab Posted October 11, 2007 Report Share Posted October 11, 2007 Without a pump continously pulling a vacumn the gas and water vapour would quickly build up in the low pressure area at the top. You cant just vent the air from there as the pressue is lower than outside, you have to pump it. Cheers Ian Quote Link to comment Share on other sites More sharing options...
paul_r Posted October 11, 2007 Report Share Posted October 11, 2007 i just had a little test while doing the dishes, i took a cup, half filled with water and put upside down (in the water), air went to the bottom of glass (the top because it is upside down), Air is lighter than water, air stays at top, no more water comes in. (no water pump is required to keep water in the glass) It looks like there is an airtight compartment at the top of the tank which has an air pump which is feeding air to the airstone, bubbles are riseing to top of compartment and being reused. I have seen similar with a tank which has feeding holes in the side of the tank, the only way it works is because the tank is packed with water and no air, therefore causeing a vacume and does not let air in or water escape Quote Link to comment Share on other sites More sharing options...
Ianab Posted October 11, 2007 Report Share Posted October 11, 2007 You are correct about how the vacumn is holding up the water, and it will stay there for a while (days even) But over time evaporation and gas release will increase the airgap in the top. Becasue the pressure in the top tank is lower, dissolved gasses will escape from the water and it will evaporate faster. After a week I bet the top tank would only be 1/2 full if there wasn't a pump maintaining the vacumn. As you have to pump out the air from the airstone anyway, just use a pump that can pump air or water without blowing itself up and it will maintain the vacumn. I bet the outlet from that pump is what is running down the little waterfall. Cheers Ian Quote Link to comment Share on other sites More sharing options...
jayci Posted October 11, 2007 Report Share Posted October 11, 2007 search The Romaurie-Effect. And there you will find the answer. Happy building people Quote Link to comment Share on other sites More sharing options...
Robert Smith Posted October 15, 2007 Report Share Posted October 15, 2007 He's pumping air out of the top of the tank. If you don't do this it will eventually empty out (drop out the hole in the bottom!) because of the air bubbler and evaporation. You need a powerful air pump to do this. You are effectively lifting the weight of all that water. The higher the tank the more powerful the pump required. This is very cool, but has some downsides: - If any seal fails to any degree or your pump fails and you don't notice (like you're on holiday) then you get one hellova mess. - The oxygen content of the water is likely to be lower than normal. This is because the air in the top of the tank is at lower pressure than atmospheric (the weight of the water reduces the pressure in the air space, or creates a partial vacuum). I think that for every 1m of water height (before any air gets in), you get about a 10% drop in atmospheric pressure, which means a 10% drop in O2 content in the water. This is compounded by the high humidity of the air in this space. High humidity also reduces dissolved oxygen (as does temperature). Quote Link to comment Share on other sites More sharing options...
jayci Posted October 15, 2007 Report Share Posted October 15, 2007 The guy is most likely using a refridgetor motor/compressor. Quote Link to comment Share on other sites More sharing options...
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