Closed Loop Vs. Tunze Streams - Page 3

goby1 · 04/27/2006, 02:56 PM

In my dictionary, the 30th definition for head refers to what you are saying about all combined pressures, and it is referenced as a loose definition. The 31st entry describes it as the vertical distance between two points in a liquid, and the pressure differential resulting from this difference. I'd tend to stick with the rigorous definition in the context of science and engineering.

Efficiency is whatever you feel like calling it... depending on the desired result. The refrigerator is 100% efficient at heating your house, as is the space heater. The submerged powerhead is 100% efficient at creating heat in the water. When you say "power out," are you referring to the power transferred to moving the water? I'd say that a pump with an eductor is more efficient at mixing tank water, as opposed to one without, even in the case where both situations conduct heat from the pump body at the same rate, and use the same total power. In this case, more kinetic energy is stored in the water, and that seems like a reasonably desired parameter in the context of marine aquaria, and thus a good one to base efficiency on.

G1

Wazzel · 04/27/2006, 03:13 PM

Quote:

Originally posted by goby1
In my dictionary, the 30th definition for head refers to what you are saying about all combined pressures, and it is referenced as a loose definition. The 31st entry describes it as the vertical distance between two points in a liquid, and the pressure differential resulting from this difference. I'd tend to stick with the rigorous definition in the context of science and engineering.

Efficiency is whatever you feel like calling it... depending on the desired result. The refrigerator is 100% efficient at heating your house, as is the space heater. The submerged powerhead is 100% efficient at creating heat in the water. When you say "power out," are you referring to the power transferred to moving the water? I'd say that a pump with an eductor is more efficient at mixing tank water, as opposed to one without, even in the case where both situations conduct heat from the pump body at the same rate, and use the same total power. In this case, more kinetic energy is stored in the water, and that seems like a reasonably desired parameter in the context of marine aquaria, and thus a good one to base efficiency on.

G1

If you are looking to talk engineering jargon the head is the appropriate term in the way I explained it. Any one in the pump and processing industries will know excatally what you are taking about if you tell them you need a pump with X ft (or psi) of head. Also, if you ask then to calculate the head required for system they can do that also.

I do not agree with the effecencey as you are trying to explaing it. Based on your deffinicition all items are 100% efficent because they do what they were designed to do. This is not the case. Industry has accepted standard for figuring the eff. for products. The pump industry is standarized on how they do things. Check out the Hydraulic Instatute if you are interested in the standards.

What you are using is a good method of comparison, but not an efficency explanation.

elephen · 04/27/2006, 03:15 PM

Quote:

Originally posted by Wazzel
For the content or entertainment?

Content.

ReeferMonkey · 04/27/2006, 03:21 PM

Just an outsider's question, Goby1 are you involved with materials science in academia, private or public practice?

goby1 · 04/27/2006, 03:42 PM

Ok I'll take your word on the jargon. Not all items are 100% efficient at doing what they are designed to do. Refrigerators are not designed to heat your house. How do you measure the efficiency of pumps like the tunze streams? I didn't find the efficiency at pumps.org.

G1

EricM · 04/27/2006, 03:59 PM

This thread is 0% efficient at explaining anything because some people cannot apply their theories to the real world.

omeg · 04/27/2006, 04:04 PM

goby1 is correct regarding heat, but only if it's a close system. Aquariums are not closed system, so moving water can create heat in the tank or it can also cool the tank (depending on temp of air/gas it's mixing with and pressures around tank). All energy is converted, just depends on where it goes and what state it's in. IMO things are more efficient if they are better at converting one energy form to another. WE just have to agree on what that conversion is, i don't think you guys are agreeing on the same measures.

I'm no physicist, but that's pretty basic stuff no??

ReeferMonkey · 04/27/2006, 04:06 PM

Quote:

Originally posted by goby1
Ok I'll take your word on the jargon. Not all items are 100% efficient at doing what they are designed to do. Refrigerators are not designed to heat your house. How do you measure the efficiency of pumps like the tunze streams? I didn't find the efficiency at pumps.org.

G1

Now I work in a design field, so maybe I don't grasp the intricacies of this (that and I did REALLY bad in solid state device physics), wouldn't the efficiency have something to do with how much energy was translated to heat vs. how much was translated into flow?

Again, maybe a noob assumption, but you make it sound like that you can't measure it just because no one has.

dvanacker · 04/27/2006, 05:14 PM

ReeferMonkey ...thats what I thought. But apparently all energy is eventually translated into heat. This thread is getting insane. I wish Einstien was here to clear this up.

goby1 · 04/27/2006, 06:27 PM

Eric, just assume a 50W mag drive in the water has the same effect as a 50W ebo jager, in terms of heating your water.

No matter the efficiency, all wattage of a submersed pump goes to heat. The only way to avoid all of your pump's wattage going to heat the water is to mount it externally.

Efficiency is a separate issue. It seems that efficiency is standardized for pump flow as (discharge pressure of the pump)(volumetric flow rate)/(input torque)(angular velocity). I would imagine that measuring the volumetric flow would be hard to measure for a propeller pump. For pumps that have a shroud, there is a well defined path for the water to move through. Not so for a free propeller.

Separately, it is my opinion that flow is not the determining factor for pumping in our hobby. It might be if you were industrially transferring fluids from one container to another, or passing them through stages (like uv sterilizer, for instance). But the display/refugium dynamics are more intricate. The distribution of the flow becomes more important. You might even want less flow if you could make up for it with a flow distributed more appropriately, as in the case with mixing eductors.

I think these are all important considerations. The original question asked for a comparison between closed loops with external pumps, and propellers with submerged motors. Three of the most relevant factors are efficiency, heat transfer, and distribution of flow.

G1

twon8 · 04/27/2006, 06:59 PM

Quote:

Originally posted by goby1
Eric, just assume a 50W mag drive in the water has the same effect as a 50W ebo jager, in terms of heating your water.

No matter the efficiency, all wattage of a submersed pump goes to heat. The only way to avoid all of your pump's wattage going to heat the water is to mount it externally.

G1

if all its watts are going to heat then what is operating the pump. if this were true the pump would be operating on some magical invisible power eminating from the ether.

twon8 · 04/27/2006, 07:10 PM

Quote:

Originally posted by goby1

Separately, it is my opinion that flow is not the determining factor for pumping in our hobby. It might be if you were industrially transferring fluids from one container to another, or passing them through stages (like uv sterilizer, for instance). But the display/refugium dynamics are more intricate. The distribution of the flow becomes more important. You might even want less flow if you could make up for it with a flow distributed more appropriately, as in the case with mixing eductors.
G1

and the tunze's on a multicontroller will produce a flow that has all my acros pe during the day, and those in the most flow seem to grow the fastest. it is true that simply having 100x turnover in a tank isn't the answer if it is coming out of one outpur and is neverchanging, but what makes the tunze so good is the changing of the multicontroller.

roader247 · 04/27/2006, 07:31 PM

If you have the money take a look at the Vortec pumps Icecap has released really good flow and low power and most of it is on the outside of the tank

Qwiv · 04/27/2006, 08:16 PM

Quote:

Originally posted by goby1
Eric, just assume a 50W mag drive in the water has the same effect as a 50W ebo jager, in terms of heating your water.

No matter the efficiency, all wattage of a submersed pump goes to heat. The only way to avoid all of your pump's wattage going to heat the water is to mount it externally.

Efficiency is a separate issue. It seems that efficiency is standardized for pump flow as (discharge pressure of the pump)(volumetric flow rate)/(input torque)(angular velocity). I would imagine that measuring the volumetric flow would be hard to measure for a propeller pump. For pumps that have a shroud, there is a well defined path for the water to move through. Not so for a free propeller.

Separately, it is my opinion that flow is not the determining factor for pumping in our hobby. It might be if you were industrially transferring fluids from one container to another, or passing them through stages (like uv sterilizer, for instance). But the display/refugium dynamics are more intricate. The distribution of the flow becomes more important. You might even want less flow if you could make up for it with a flow distributed more appropriately, as in the case with mixing eductors.

I think these are all important considerations. The original question asked for a comparison between closed loops with external pumps, and propellers with submerged motors. Three of the most relevant factors are efficiency, heat transfer, and distribution of flow.

G1

Just had to read this thread and saw this guy talking. Dude, you haven't even seen a tunze from an earlier post so all you comments are a joke. According to your logic, if i put a 50 watt light inside my tank (in the water) then it would be the same as a 50 watt heater. What about the LIGHT it produces!!! A motor uses most of its energy to create a magnetic field. The heat comes from resistance in the motor/wire/etc.

To the poster, I have both a closed loop, tunzes and a return on my tank 180. I use (2) 6100 to produce the gentle low velocity, large volume water movement in the tank. This is the life blood of the tank. I have an Ampmaster 3000 or a dart, on the overhead closed loop. This provides flow to dead spots in my tank due to my creative rock work. I can also target this at specifive corals using the locline. My return is on a sea swirl/penductor.

I will tell you for certain that the dart or the amp master raised the tank temp way more than both the tunze's at 100% and produces 1/2 the flow at 2x the energy consumption.
The return pump/sea swirl/penductor works great, but don't point it directly at a coral. It produces more heat, less flow and uses more electricity than the tunzes.

I can't choose which one is best for you as I like them all. Obviously.

I would really look at the new icecap pumps. They look great from the reviews and are much smaller than the tunze + even less heat as they are external.

Qwiv · 04/27/2006, 08:26 PM

Quote:

Originally posted by goby1
A submerged 45W powerhead will heat the water the same as a 45W heater. Physics 101...

What is it that makes a Tunze so efficient? I've never looked at one up close, but why couldn't you use one in a closed loop? Are we sure they move 3175gph? I'm just a bit puzzeled on this efficency....

G1

dude, if you have never seen, used or touched a Tunze, how can you tell someone there not as good, better or worse then a closed closed loop? Besides Physics 101.

goby1 · 04/27/2006, 09:12 PM

Why do you have to get ****ed when I'm just trying to explain the second law of thermodynamics in the context of this hobby. I'm trying to help out. Calling my effort, in creating these posts and wording them such that you can understand, a joke, is upsetting, and I don't think it's in the spirit of this forum to do that.

Paint the bulb black, or the tank, and it would. Twon, let's say the submerged pump is 40% efficient. That means that 60% of the watts are conducted away from the pump body as heat, and the other 40% heats the water throughout the water column as it is a resistive fluid. The water column continually dissipates heat, which is why you need to devote your 40% to balance this.

Newton: Object in motion tends to stay in motion unless acted upon by a force.

If you turn off the pumps, does the water keep on moving? Why not?

I'm not making any judgement calls on good, better or worse in general. I know now that a tunze is a motor with a propellor on it, and it is submerged in the water. I'm puzzeled on the efficiency because I don't know how flow from a propeller is measured.

Repeat: If you turn off the pumps, does the water keep on moving? Why not?

G1

Qwiv · 04/27/2006, 09:53 PM

Paint the light bulb black, are you kidding me. OK. Then a pump will become a heater when you restrict the pump so that it does not move. THEN you have a 50 watt pump becoming a 50 watt heater. Try it, pumps heat up really good when you make them stick like that. Until you do that, the pump is not a 50 watt heater and you just proved yourself incorrect.

Dude, you are stretching the laws of thermodynamics into this hobby way to hard. First, the second law can not be used in a reef tank in therms of thermo dynamics, as a reef tank is not a closed system. It reacts with the livingroom or where ever the tank is. Plus we are constantly adding energy to the system. If you want to do that we might as well say moving water in the tank is heating it, as heat is most simply defined as motion. If any of these things could be applied, keeping a reeftank would just be impossible.

I know in theory all energy will eventually result in heat in a closed system, but this is not a closed system. In terms of a pump, lets trace the flow of energy. Electricity -> pump makes magnetic field + heat. Magnetic field -> kinetic energy + heat. Kinetic energy -> heat + calcification in corals + increased gas exchange evaporation (- heat) + a bunch of chemical reactions that are insignificant. OK, now heater. Electricity -> heat + maybe some light. See the difference?

Efficiency. You can use it at least (2) different ways when when talking about a pump. (1) Pump x uses 100 watts and moves 100 gph. Pump y uses 100 watts and moves 50 gph. Pump y is therefore 50% as efficient as pump x in terms of moving water. (2) Pump x uses 100 watts and produces 100 gpm + heat. 100 gpm = y% of 100 watts energy and heat = z% of 100 watts of energy. Therefore pump x is y% efficient at moving water and z% efficient at producing heat. Most people are referring to example #1.

To answer your ?, If you turn the pumps off the water will and will not continue to move. Most of the water will stop due to resistance, a small percentage will continue to move due to convection currents, gas exchange, etc.

goby1, you should move this discussion to another thread as this is not helping the poster answer his questions. Maybe put this in the advanced section.

goby1 · 04/27/2006, 10:06 PM

The second law can be applied to any physical system, including the reef tank.

You're right, we are constantly adding energy to the system. And what happens to that energy? It doesn't go to increase the kinetic energy in the water, otherwise the water would continue to accelerate.

Before you turn off the pump, the water has kinetic energy. When the water has stopped moving, where has this energy gone?

I'll start a thread in advanced.

G1

Qwiv · 04/27/2006, 10:10 PM

sorry, I was editing my post as you posted. I addressed your ? in the edit. Read it again.

Qwiv · 04/27/2006, 10:11 PM

simple definition of thermodynamics
"the entropy of any totally isolated system not at thermal equilibrium will tend to increase over time, approaching a maximum value." ("Isolated" means the system is insulated from any thermodynamic interaction with its environment)

A reeftank does not meet that definition by the fact that water evaporates into an outside system.

Mike.B · 04/27/2006, 10:28 PM

wow, this is getting deep!

twon8 · 04/27/2006, 10:39 PM

both pumps are transfering watts into work to move water, which then has kinetic energy. so if i want to move 6000gph, i need to put the energy/heat into the water and in my eye that can be done the most efficiently with a tunze. but what convinces me is the look and health of the corals, something hard to show on here. pictures can be seen by clicking my red house, the best/only proof i can offer.

by your thinking, how many watts of power does the external pump you use transfer into both:
heat in the water
energy into the water
heat into the surrounding room.

goby1 · 04/27/2006, 11:55 PM

Addressed in my post in the advanced forum. It also all goes to heat the room too. Consider the room to be adiabatic, and it is a closed system with respect to thermal transfer, and mechanical transfer if the walls are rigid. The maximum in entropy occurs when the system is most disordered, and considering the higher number of microstates available for the macrostate that is associated with the system at the highest temperature, the most disordered state is that at highest temperature. This is the statistical mechanics way of stating the second law. The first law says that energy is conserved, and the second that it will all go to thermal energy if it is allowed to react. Thermodynamics says nothing of the rates at which processes happen, only their direction. Kinetic factors affect rates.

If you were to insulate your tank perfectly, with a motor outside the insulation, and a shaft connected to a propeller inside, and turn on the motor, the temperature would continue to rise forever inside. In a non-pefectly insulated tank, all work in equals all work out, if the combined kinetic and potential energies inside remain the same. The water moves at the same rate on average inside the tank (constant kinetic energy), and there are no gravitational or chemical means to store potential energy, so all work in (pump wattage) equals all work out. How is this energy being transferred out of the tank? There is no material leaving, so there is no chemical work, and the walls are not expanding, so there is no pressure-volume work.... it comes out at a constant rate, as heat. With the non-perfectly insulated box with the propeller inside, the temperature inside will be higher than the surroundings. The raise will be proportional to the thickness of the material, and inversely proportional to the thermal conductivity of the material and the dimensions of the box. Again, the temperature will increase inside the box, even with the motor outside. See my post in advanced.

G1

Wazzel · 04/28/2006, 06:06 AM

Quote:

Originally posted by goby1
Ok I'll take your word on the jargon. Not all items are 100% efficient at doing what they are designed to do. Refrigerators are not designed to heat your house. How do you measure the efficiency of pumps like the tunze streams? I didn't find the efficiency at pumps.org.

G1

Sory I did not respond yesterday. I'm overseas right now and had to go to work.

If I was interested in getting a rough eff for a stream I would use this equation

P=(Q*H*SG)/(Eff*3960)

I would have to make 2 assumptions

first head loose is 1ft
Second eff is 100%

This would give me the theortical min power required.

Devide this by the published power draw to get the Eff of the pump, motor and controler. Again this is a rough number.

If I was doing a bench mark performance test this is what I would do.

First attach a tube to the output of the pump. In this tub I would have, comming from the pump out. a pressure gauge, flow meter (probably an orfice plate) then a valve. I would also have on the power to the motor somthing to measure current, volts and amps. I would take the pump/tube assy and submerge it in a tank of water.

I would run the pump with no restirction down to completly close in equal flow devisions, atleast 7 point. I would measure the following at each poing.

Flow
Pressure
Current
volts
amps

From these data points I could calculate the Hp of the water and the Hp (watts) of the electricity being used. From this I could calculate the eff of the pump and motor. Also, I could create a head-capacity curve and show the entire pump performance from shut off to run out.

I use to design and test pumps for a living. Biggest I worked on was a 4000 hp, 250,000 GPM vetrical line shaft pump.

Mogrash · 04/28/2006, 09:00 AM

To the originator of the post..

Assuming you only care about the health of your animals:

I think Tunze will give you the best overall control/options of replicating various forms of the reef assuming you buy at least 2 (even better 4) pumps with a multicontroller (expensive): http://www.tunze.com/149.html?&L=1&C..._tunzeprod_pi1[predid]=-infoxunter015

Closed loops can be setup with some careful planning to simulate any of these areas, too. But once setup it would be hard to change unless replumbing or changing pump size. With a Tunze if you are sick of one setting you can change it. Not to mention feeding time is a breeze with the multicontroller. For me, that was worth the price alone.

In the end, with a Tunze you are paying for flexibility, adaptability and convenience (plus no plumbing!).

04/27/2006, 05:14 PM	#59
dvanacker DID I SOUNDS SMRT?? Join Date: Aug 2005 Location: Ontario, CAN Posts: 3,690	ReeferMonkey ...thats what I thought. But apparently all energy is eventually translated into heat. This thread is getting insane. I wish Einstien was here to clear this up. __________________ --DARRYL-- Current Tank Info: 200g SPS dominant Mixed Reef

04/27/2006, 07:31 PM	#63
roader247 Registered Member Join Date: Aug 2005 Location: Athens GA Posts: 657	If you have the money take a look at the Vortec pumps Icecap has released really good flow and low power and most of it is on the outside of the tank __________________ Old Enough too Know Better But Young Enough Too Do It Anyway Mark Current Tank Info: 1 75 gallon fish only marine tank 1 55 fresh water tank and 1 29 gallon fresh tank

04/27/2006, 09:53 PM	#67
Qwiv Persistant Perspective Join Date: Nov 2003 Location: Belmont, CA Posts: 2,168	Paint the light bulb black, are you kidding me. OK. Then a pump will become a heater when you restrict the pump so that it does not move. THEN you have a 50 watt pump becoming a 50 watt heater. Try it, pumps heat up really good when you make them stick like that. Until you do that, the pump is not a 50 watt heater and you just proved yourself incorrect. Dude, you are stretching the laws of thermodynamics into this hobby way to hard. First, the second law can not be used in a reef tank in therms of thermo dynamics, as a reef tank is not a closed system. It reacts with the livingroom or where ever the tank is. Plus we are constantly adding energy to the system. If you want to do that we might as well say moving water in the tank is heating it, as heat is most simply defined as motion. If any of these things could be applied, keeping a reeftank would just be impossible. I know in theory all energy will eventually result in heat in a closed system, but this is not a closed system. In terms of a pump, lets trace the flow of energy. Electricity -> pump makes magnetic field + heat. Magnetic field -> kinetic energy + heat. Kinetic energy -> heat + calcification in corals + increased gas exchange evaporation (- heat) + a bunch of chemical reactions that are insignificant. OK, now heater. Electricity -> heat + maybe some light. See the difference? Efficiency. You can use it at least (2) different ways when when talking about a pump. (1) Pump x uses 100 watts and moves 100 gph. Pump y uses 100 watts and moves 50 gph. Pump y is therefore 50% as efficient as pump x in terms of moving water. (2) Pump x uses 100 watts and produces 100 gpm + heat. 100 gpm = y% of 100 watts energy and heat = z% of 100 watts of energy. Therefore pump x is y% efficient at moving water and z% efficient at producing heat. Most people are referring to example #1. To answer your ?, If you turn the pumps off the water will and will not continue to move. Most of the water will stop due to resistance, a small percentage will continue to move due to convection currents, gas exchange, etc. goby1, you should move this discussion to another thread as this is not helping the poster answer his questions. Maybe put this in the advanced section. __________________ If I knew keeping fish would be so hard, I would of had kids by now. Current Tank Info: 50Cube + 250DD + Nano Last edited by Qwiv; 04/27/2006 at 10:08 PM.

04/27/2006, 10:10 PM	#69
Qwiv Persistant Perspective Join Date: Nov 2003 Location: Belmont, CA Posts: 2,168	sorry, I was editing my post as you posted. I addressed your ? in the edit. Read it again. __________________ If I knew keeping fish would be so hard, I would of had kids by now. Current Tank Info: 50Cube + 250DD + Nano

04/27/2006, 10:11 PM	#70
Qwiv Persistant Perspective Join Date: Nov 2003 Location: Belmont, CA Posts: 2,168	simple definition of thermodynamics "the entropy of any totally isolated system not at thermal equilibrium will tend to increase over time, approaching a maximum value." ("Isolated" means the system is insulated from any thermodynamic interaction with its environment) A reeftank does not meet that definition by the fact that water evaporates into an outside system. __________________ If I knew keeping fish would be so hard, I would of had kids by now. Current Tank Info: 50Cube + 250DD + Nano

04/27/2006, 02:56 PM	#51
goby1 Premium Member Join Date: Feb 2004 Location: san francisco Posts: 364	In my dictionary, the 30th definition for head refers to what you are saying about all combined pressures, and it is referenced as a loose definition. The 31st entry describes it as the vertical distance between two points in a liquid, and the pressure differential resulting from this difference. I'd tend to stick with the rigorous definition in the context of science and engineering. Efficiency is whatever you feel like calling it... depending on the desired result. The refrigerator is 100% efficient at heating your house, as is the space heater. The submerged powerhead is 100% efficient at creating heat in the water. When you say "power out," are you referring to the power transferred to moving the water? I'd say that a pump with an eductor is more efficient at mixing tank water, as opposed to one without, even in the case where both situations conduct heat from the pump body at the same rate, and use the same total power. In this case, more kinetic energy is stored in the water, and that seems like a reasonably desired parameter in the context of marine aquaria, and thus a good one to base efficiency on. G1

04/27/2006, 03:21 PM	#54
ReeferMonkey Premium Member Join Date: Feb 2003 Location: San Diego CA Posts: 1,099	Just an outsider's question, Goby1 are you involved with materials science in academia, private or public practice?

04/27/2006, 03:42 PM	#55
goby1 Premium Member Join Date: Feb 2004 Location: san francisco Posts: 364	Ok I'll take your word on the jargon. Not all items are 100% efficient at doing what they are designed to do. Refrigerators are not designed to heat your house. How do you measure the efficiency of pumps like the tunze streams? I didn't find the efficiency at pumps.org. G1

04/27/2006, 03:59 PM	#56
EricM Registered Member Join Date: Apr 2003 Location: Maryland Posts: 181	This thread is 0% efficient at explaining anything because some people cannot apply their theories to the real world.

04/27/2006, 04:04 PM	#57
omeg Registered Member Join Date: Mar 2006 Location: Home of Angels, Ducks, and a mouse Posts: 395	goby1 is correct regarding heat, but only if it's a close system. Aquariums are not closed system, so moving water can create heat in the tank or it can also cool the tank (depending on temp of air/gas it's mixing with and pressures around tank). All energy is converted, just depends on where it goes and what state it's in. IMO things are more efficient if they are better at converting one energy form to another. WE just have to agree on what that conversion is, i don't think you guys are agreeing on the same measures. I'm no physicist, but that's pretty basic stuff no??

04/27/2006, 06:27 PM	#60
goby1 Premium Member Join Date: Feb 2004 Location: san francisco Posts: 364	Eric, just assume a 50W mag drive in the water has the same effect as a 50W ebo jager, in terms of heating your water. No matter the efficiency, all wattage of a submersed pump goes to heat. The only way to avoid all of your pump's wattage going to heat the water is to mount it externally. Efficiency is a separate issue. It seems that efficiency is standardized for pump flow as (discharge pressure of the pump)(volumetric flow rate)/(input torque)(angular velocity). I would imagine that measuring the volumetric flow would be hard to measure for a propeller pump. For pumps that have a shroud, there is a well defined path for the water to move through. Not so for a free propeller. Separately, it is my opinion that flow is not the determining factor for pumping in our hobby. It might be if you were industrially transferring fluids from one container to another, or passing them through stages (like uv sterilizer, for instance). But the display/refugium dynamics are more intricate. The distribution of the flow becomes more important. You might even want less flow if you could make up for it with a flow distributed more appropriately, as in the case with mixing eductors. I think these are all important considerations. The original question asked for a comparison between closed loops with external pumps, and propellers with submerged motors. Three of the most relevant factors are efficiency, heat transfer, and distribution of flow. G1

04/27/2006, 09:12 PM	#66
goby1 Premium Member Join Date: Feb 2004 Location: san francisco Posts: 364	Why do you have to get ****ed when I'm just trying to explain the second law of thermodynamics in the context of this hobby. I'm trying to help out. Calling my effort, in creating these posts and wording them such that you can understand, a joke, is upsetting, and I don't think it's in the spirit of this forum to do that. Paint the bulb black, or the tank, and it would. Twon, let's say the submerged pump is 40% efficient. That means that 60% of the watts are conducted away from the pump body as heat, and the other 40% heats the water throughout the water column as it is a resistive fluid. The water column continually dissipates heat, which is why you need to devote your 40% to balance this. Newton: Object in motion tends to stay in motion unless acted upon by a force. If you turn off the pumps, does the water keep on moving? Why not? I'm not making any judgement calls on good, better or worse in general. I know now that a tunze is a motor with a propellor on it, and it is submerged in the water. I'm puzzeled on the efficiency because I don't know how flow from a propeller is measured. Repeat: If you turn off the pumps, does the water keep on moving? Why not? G1

04/27/2006, 10:06 PM	#68
goby1 Premium Member Join Date: Feb 2004 Location: san francisco Posts: 364	The second law can be applied to any physical system, including the reef tank. You're right, we are constantly adding energy to the system. And what happens to that energy? It doesn't go to increase the kinetic energy in the water, otherwise the water would continue to accelerate. Before you turn off the pump, the water has kinetic energy. When the water has stopped moving, where has this energy gone? I'll start a thread in advanced. G1

04/27/2006, 10:28 PM	#71
Mike.B Registered Member Join Date: Jan 2004 Location: Canada Posts: 548	wow, this is getting deep!

04/27/2006, 10:39 PM	#72
twon8 Formally registered membe Join Date: Oct 2003 Location: slightly sw of richmond, va Posts: 5,920	both pumps are transfering watts into work to move water, which then has kinetic energy. so if i want to move 6000gph, i need to put the energy/heat into the water and in my eye that can be done the most efficiently with a tunze. but what convinces me is the look and health of the corals, something hard to show on here. pictures can be seen by clicking my red house, the best/only proof i can offer. by your thinking, how many watts of power does the external pump you use transfer into both: heat in the water energy into the water heat into the surrounding room. __________________ Anthony Richmond Reef Club "and as things fell apart, nobody paid much attention." Not building a wall but making a brick Current Tank Info: 300g DD display, 60g frag tank

04/27/2006, 11:55 PM	#73
goby1 Premium Member Join Date: Feb 2004 Location: san francisco Posts: 364	Addressed in my post in the advanced forum. It also all goes to heat the room too. Consider the room to be adiabatic, and it is a closed system with respect to thermal transfer, and mechanical transfer if the walls are rigid. The maximum in entropy occurs when the system is most disordered, and considering the higher number of microstates available for the macrostate that is associated with the system at the highest temperature, the most disordered state is that at highest temperature. This is the statistical mechanics way of stating the second law. The first law says that energy is conserved, and the second that it will all go to thermal energy if it is allowed to react. Thermodynamics says nothing of the rates at which processes happen, only their direction. Kinetic factors affect rates. If you were to insulate your tank perfectly, with a motor outside the insulation, and a shaft connected to a propeller inside, and turn on the motor, the temperature would continue to rise forever inside. In a non-pefectly insulated tank, all work in equals all work out, if the combined kinetic and potential energies inside remain the same. The water moves at the same rate on average inside the tank (constant kinetic energy), and there are no gravitational or chemical means to store potential energy, so all work in (pump wattage) equals all work out. How is this energy being transferred out of the tank? There is no material leaving, so there is no chemical work, and the walls are not expanding, so there is no pressure-volume work.... it comes out at a constant rate, as heat. With the non-perfectly insulated box with the propeller inside, the temperature inside will be higher than the surroundings. The raise will be proportional to the thickness of the material, and inversely proportional to the thermal conductivity of the material and the dimensions of the box. Again, the temperature will increase inside the box, even with the motor outside. See my post in advanced. G1

04/28/2006, 09:00 AM	#75
Mogrash Registered Member Join Date: Sep 2004 Posts: 212	To the originator of the post.. Assuming you only care about the health of your animals: I think Tunze will give you the best overall control/options of replicating various forms of the reef assuming you buy at least 2 (even better 4) pumps with a multicontroller (expensive): http://www.tunze.com/149.html?&L=1&C..._tunzeprod_pi1[predid]=-infoxunter015 Closed loops can be setup with some careful planning to simulate any of these areas, too. But once setup it would be hard to change unless replumbing or changing pump size. With a Tunze if you are sick of one setting you can change it. Not to mention feeding time is a breeze with the multicontroller. For me, that was worth the price alone. In the end, with a Tunze you are paying for flexibility, adaptability and convenience (plus no plumbing!).