Hamster water bottle ATO for pico.

[Jan]

Can someone expain how this works? I found a thread on nano reef but i just don't get it.

 

 

[Origami]

Jan, I think you have to remove the ball that normally seals the tube to get this to work. It's like an automatic pet waterer. When the water level falls below the opening of the tubing, it allows air to pass up into the water bottle, replacing the water that's flowing out. When the water level rises to cover the opening, air cannot get back up into the bottle and the water is held up in the bottle by the reduced air pressure inside the bottle.

 

You can do the same thing with a regular old disposable water bottle with a hole drilled in the cap.

[davelin315]

That will rust and also your top off will eventually mix in with the rest of the water because of the water trying to reach equilibrium, at least that's my opinion.

 

One option to prevent this is to use a compression coupling and put a ping pong ball in it. When the water is up at the top, it will float up and create a seal with the gasket, when it's lower down, it should allow water to flow out.

[DaveS]

also your top off will eventually mix in with the rest of the water because of the water trying to reach equilibrium, at least that's my opinion.

 

Actually I'm not sure this is the case. Salt water is heavier than fresh so in the absence of any turbulence, it should stratify.

[Hilary]

Interesting! I was wondering how to handle topoff with my little pico!

[davelin315]

Actually I'm not sure this is the case. Salt water is heavier than fresh so in the absence of any turbulence, it should stratify.

Good point, but I don't know of any places where there wouldn't be any flow in a tank - I would think that the slightest current would cause it to mix together, at least to some degree.

[Jan]

Tom,

How can I do this with a disposable water bottle? Where can I drill the whole? What about using a water bottle that has a push top? I'm trying to figure out how to keep the bottle in place.

 

Jan, I think you have to remove the ball that normally seals the tube to get this to work. It's like an automatic pet waterer. When the water level falls below the opening of the tubing, it allows air to pass up into the water bottle, replacing the water that's flowing out. When the water level rises to cover the opening, air cannot get back up into the bottle and the water is held up in the bottle by the reduced air pressure inside the bottle.

 

You can do the same thing with a regular old disposable water bottle with a hole drilled in the cap.

[luceneck]

Tom,

How can I do this with a disposable water bottle? Where can I drill the whole? What about using a water bottle that has a push top? I'm trying to figure out how to keep the bottle in place.

 

 

You may want to look through some of the Solana threads on RC and Nano-Reef. The top off unit at the back is configured to work in that upside down bottle format. Sorry, not much info in my post

Edited November 18, 2009 by luceneck

[Origami]

Tom,

How can I do this with a disposable water bottle? Where can I drill the whole? What about using a water bottle that has a push top? I'm trying to figure out how to keep the bottle in place.

 

There might be good threads on it where Luceneck was pointing. I've not seen them.

 

However, you would just drill a hole in the screw cap of the water bottle. The hole has to be wide enough in cross section to reliably allow air to overcome the surface tension at the hole, though. (This integrity of the tension to hold this seal would likely vary with the material interface at the hole - whether it was plastic or metal, for example.) Just as an experiment this morning, I took a regular smallish water bottle (16 or so ounces), filled it 3/4 with water, and drilled the cap with successively larger holes until I saw reliable draining occur out of the inverted bottle. In this experiment, I had to drill successively larger holes from 1/8" upwards in 1/8" increments until I had drilled a 1/2" hole in the cap. Even then, to get really reliable drainage, I found that I could tip the bottle a few degrees (<5) and improve drainage reliability. When the bottle cap was then immersed, the draining stopped (as evidenced by the bubbles stopping). This was a really simple experiment. As they say, your mileage may vary.

[Happyfeet]

That will rust

 

I can't say if the addition of salt on the exterior of the tube will cause it to or not, but Freshwater won't case this to rust. Never had a problem with my piggies bottle.

[zygote2k]

easy cheesy way- every morning just pour a little freshwater in.

[DaveS]

Good point, but I don't know of any places where there wouldn't be any flow in a tank - I would think that the slightest current would cause it to mix together, at least to some degree.

 

Hmm maybe I misunderstood when I quickly read the posts. I thought the issue being addressed was- how to make sure the fresh water in the inverted bottle/hamster bottle without a ball doesn't get mixed with the salt water. I believe that if you have fresh water in the bottle and invert it with the opening submerged in the salt water, the water in the bottle will stay fresh. You could have typical flow in the salt water portion and short of pointing a jet up the opening, the fresh water will stay fresh in the bottle.

 

Since salt is dissolved into solution, it's particles are not subject to t diffusion in the way that Dalton's Law of Partial Pressure says a gas does. Maybe I'm wrong...

[davelin315]

Hmm maybe I misunderstood when I quickly read the posts. I thought the issue being addressed was- how to make sure the fresh water in the inverted bottle/hamster bottle without a ball doesn't get mixed with the salt water. I believe that if you have fresh water in the bottle and invert it with the opening submerged in the salt water, the water in the bottle will stay fresh. You could have typical flow in the salt water portion and short of pointing a jet up the opening, the fresh water will stay fresh in the bottle.

 

Since salt is dissolved into solution, it's particles are not subject to t diffusion in the way that Dalton's Law of Partial Pressure says a gas does. Maybe I'm wrong...

Hmmm... you're now beyond my rudimentary knowledge of physics... wouldn't the water, given any agitation at all, mix between the two vessels? Or is this simply when dealing with side by side liquids that will reach equilibrium? I'll have to experiment at home with this to see what happens. The picture shows it not mixing, and since salt water is heavier, it makes sense that it wouldn't mix up into the vessel, but I would think that the point of contact between fresh and salt would cause them to slowly mix together, diluting the water below and salting the water above?

[Origami]

I can see the validity to Dave Sun's thinking. The same clear separation due to density differences exist in estuaries where there is an interface between salt and fresh water. There is an analogous phemenon at work in a thermocline, where there can exist distinct temperature bands within the same body of water - again, due to density differences. There are enen examples of clear stratification by salinity in the ocean both at the surface, which may be exposed to large amounts of rainfall in some regions, and at depth.

 

My thought is that suchl strata could not last forever, even under static conditions, because the enthalpy manifested in the interface would eventually give way to entropy (as long as no other energy is invested in the system). However, it need not happen rapidly and the separation could persist a very long time. Perhaps weeks or more.

 

The important question here may be the practical one. It's easily tested, I suppose. But I wonder if the thread pointed out earlier offers this practical insight? However, as you can see from the pictures in Jan's original post, there is clear separation being main

ained between the pink water in the beaker and the clear water in the hamster bottle. It seems to me that whoever set this up was trying also to demonstrate that diffusion was not a serious concern here (else why add the dye to the setup!).

.

[L8 2 RISE]

I can see the validity to Dave Sun's thinking. The same clear separation due to density differences exist in estuaries where there is an interface between salt and fresh water. There is an analogous phemenon at work in a thermocline, where there can exist distinct temperature bands within the same body of water - again, due to density differences. There are enen examples of clear stratification by salinity in the ocean both at the surface, which may be exposed to large amounts of rainfall in some regions, and at depth.

 

My thought is that suchl strata could not last forever, even under static conditions, because the enthalpy manifested in the interface would eventually give way to entropy (as long as no other energy is invested in the system). However, it need not happen rapidly and the separation could persist a very long time. Perhaps weeks or more.

 

The important question here may be the practical one. It's easily tested, I suppose. But I wonder if the thread pointed out earlier offers this practical insight? However, as you can see from the pictures in Jan's original post, there is clear separation being main

ained between the pink water in the beaker and the clear water in the hamster bottle. It seems to me that whoever set this up was trying also to demonstrate that diffusion was not a serious concern here (else why add the dye to the setup!).

.

 

Is it just me or does he try to use big/ unknown words to make people reread his posts multiple times in order to understand it? Luckily I have a test on entropy and enthalpy tomorrow and I actaully understood this one .

 

I'll make mine short: I'd guess that the two will not mix based on the greater density of the salt water and I can't see the salt water "creaping" up into the hamster bottle if the water in the tank is going to be topped off by the fresh water pretty usually. I don't know if this was the case with the picture, but a better way to test if it works would be to have pink colored SALT water in the cup with a lot of flow going through it, and clear fresh water in the hamster bottle. If I get time, I think I might have a few hamster bottles left over that I could try this with.

 

Also, I just remembered an experiment I did back in 8th grade where we put tap water into a graduated cylinder, then measured the density of an egg, mixed something into another sample of water (can't remember what, but it MAY have been salt) so that it ended up with a higher density than the egg. We then put the egg into the fresh water that was in the graduated cylinder (it sank to the bottom), and used a tube to siphon the higher density water into the area beneath the egg (we had to be careful not to cause to much disturbance or risk mixing the two water samples together). The egg ended up suspended half way up in the graduated cylinder and slowly sank down over the course of a couple weeks.

[extreme_tooth_decay]

This reminds me of that upside-down fish tank someone posted a youtube video to a while back.

 

I think it was this one:

Edited November 19, 2009 by extreme_tooth_decay

[Origami]

Is it just me or does he try to use big/ unknown words to make people reread his posts multiple times in order to understand it? Luckily I have a test on entropy and enthalpy tomorrow and I actaully understood this one .

 

I'll make mine short: I'd guess that the two will not mix based on the greater density of the salt water and I can't see the salt water "creaping" up into the hamster bottle if the water in the tank is going to be topped off by the fresh water pretty usually. I don't know if this was the case with the picture, but a better way to test if it works would be to have pink colored SALT water in the cup with a lot of flow going through it, and clear fresh water in the hamster bottle. If I get time, I think I might have a few hamster bottles left over that I could try this with.

 

Also, I just remembered an experiment I did back in 8th grade where we put tap water into a graduated cylinder, then measured the density of an egg, mixed something into another sample of water (can't remember what, but it MAY have been salt) so that it ended up with a higher density than the egg. We then put the egg into the fresh water that was in the graduated cylinder (it sank to the bottom), and used a tube to siphon the higher density water into the area beneath the egg (we had to be careful not to cause to much disturbance or risk mixing the two water samples together). The egg ended up suspended half way up in the graduated cylinder and slowly sank down over the course of a couple weeks.

 

Neat experiment, Sam. It shows that there is some diffusion that occurs and that it's a slow process even given the comparatively large interface between the two fluids. The diffusion process should be proportional to the area of the interface, so the hamster bottle solution would probably take much longer for their to be substantial intermixing of the two fluids.

 

I'm glad that you're studying some elementary thermodynamics. It will serve you well should you go into a technical field someday.

 

Here's a decoder for that last post:

 

enen = even

suchl = such

main ained = maintained

 

The other words were as typed - and english at that. It was late (or early) depending upon your perspective, and I was typing my thoughts from my phone. That's what you get, I guess, from a fat-fingering engineer / scientist / former newsletter and newspaper editor.