Fish Highway / Fish Bridges / Fish Towers

Yeah that is pretty cool. Its amazing how the pressures in there dont harm the fish since their bodies are designed for it. Just as a by the way, the glue used on an acrylic pipe is a methyl chloride based solvent. Over here in the states we use IPS Weld On acrylic adhesives usually. Dunno what you guys use on the other side of the pond tough :)
 
PRESSURE!!!! or rather the lack of is now my concern can anyone tell me if i am correct, if i build a 1m tower there would indeed be allot of weight pulling down and surely any air at the top would be a vacume or at least very low pressure, does anyone know how much height has how much affect on the low air pressure area? it must be a formula similar to the one used to measure atmospheric pressure as i think the water line will change slightly as the air pressure fluctuates outside ermm oops i reinvented the barometer and put fish in it have i gone mad???
paul...
 
There are in fact physical properties that you can account for to figure out how big of a tower you can create. The bodies of the fish can take this stress for various reasons, so dont worry about that. As far as the water column height goes, prepare yourself for a math lesson :). So, at sea level we are all at 1 atmosphere (atm) of pressure. Thats the equivalent of having a 10.332meter column of water on top of us. There is an absoloute zero pressure you approach as you go higher and higher in that column of water. So, if water stayed the same at all pressures, you could build a 10.332meter tall column of water to have the fish in above an open body of water at sea level. Once you breached 10.332m, the negative pressure would be so great that it would suck air in pas the lip of the tube under the level in your tank and drop the water level back to no greater than 10.322m.

However, there is still another problem. Water at ambient temperature (25C) does not stay liquid at very very low pressures. As the pressure drops, so does the temperature at which water can boil at. Water boils at 25C at 47torr absoloute (sorry, another measure of pressure). So if we convert all that to units we understand, when one gets a column over 9.693m of water at 25C and at sea level above the level of the tank, the water at the top of the column WILL literally boil. Gasses and water vapor are released, and the water column will fall back to 9.693m or less.

Therefore, the theoretical max at sea level is 9.693m but probably a more safe practical max is 8m. Your suggested 1m is perfectly safe and probably wont put too much stress on any properly solvent welded joints.
 
I figured I would post these pictures here as well as they may help give some ideas. I use to build my own bubble towers. I have two 4 foot lengths of acrylic clear 6 inch PVC pipe and one 4 foot length of 3 inch clear PVC pipe. Both over kill for size and length for my one 20 gallon tank.

While I was building my bubble tanks, I made a twin tower tank that was connected by a section of clear tubing from a cheap bird feeder. The bases were just hot glued into place so I could change out the bubble stones. It did eventually leak over time, as any hot glue joint will under pressure.

Here are some picks to get creative juices flowing. The bridge does not have to be a round tube!! You could build a square bridge out of plexi glass from your hardware store. You just have to join and seal all the edges. So material is easier to get, just more labour and edges.

To seal the edges of these towers, I used a resin thats called EnviroTex Lite, a liquid glass. Not sure if its safe for fish when exposed to water.

tower1.jpg

tower2.jpg
tower3.jpg


Here is a very cheap source of acrylic tubing in 12 - 24 inch lengths. The tube wall thickness is not huge, probably a few mm, but should work for a great price.

Clear Mailing Tubes

Heh, someone should get some for em then ship to Canada :angry:
 
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Thuggerz, where did you get the tubing from?


Hi, i bought it from this ebay shop which offer a very friendly service

http://stores.ebay.co.uk/Clear-Plastic-Supplies

Have the fish used it yet? I am suprised you didn't just use 90 degree elbows instead of joining your corners to be square. Hey it works though.

I was waiting for someone to ask me if the fish have used it yet and the answer is NO!!!! I even tryed to force them up there and they still didnt want anything to do with it....waste of time!!!
 
BINGO!

Acrylic Tubing on Ebay

Thuggerz, I wonder if it has anything to do with lack of flow of water through the tube. In the article at the start of this post, the person was joining two tanks so there was a continuious flow of water. One tank held the filter putting water into the system, the other tank has the suction pulling water out. This caused a continuious flow of water from one tank to another. This might make the difference? I'll let you know once I experiment with mine. (If I ever get the fish and get the tank cycled)
 
This very cool.

...the only implication i can think of at presant is water changes (id have 2do a litre at a time :X )

I might have a solution to this and if this has already been posted, I apologize. If you can cap off the ends of the bridge, sealing the water in, then you should be able to while you are doing the water changes and then remove the caps again when the change is complete.

-Brian
 

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