pumps - where's the heat?

[Kenfuzed]

I have several pumps running on a new 180 set up and I'm trying to locate a heat source. Of the pumps listed below, which would be the biggest offender?
Dart CL (144w)
Eheim 1262 return (68w)
Vertex IN-250 (I believe the pump is a Sedra 2500, 65w draw)
WM Reactor (12w)
Tunze 6105 (30w)

All wattage was measured with a kill-a-watt.

Without lights the tank hangs around 81.4 with 2 fans and one exhaust fan drawing air/moisture from the fish room. The house is cooled via central air and kept around 75-76. All the pumps are new or in good condition. The Dart is the new Baldor version and is far cooler to the touch than my old Dart.

Any ideas?

[mick243]

any pump that is submerged will add its wattage to the tank as heat - ie, a 100w pump will add 100w of heat to the tank - some directtly as heat from the motor windings, the rest as kinetic energy imparted to the water which through friction ends up as heat.

if the pump is not submerged, this changes as some of its motor heat is lost to the air.

[James77]

What ^^ said.

The Eheim and the Sedra are your worst offenders. The Dart(and all Reeflos) add very little heat.

[PowermanKW]

You basically have a 175 watt heater on continuously.

[tydtran]

Agree with the statements about the submerged pumps, but is the temp of 81.4 causing any problems??

[Kenfuzed]

Originally posted by tydtran
Agree with the statements about the submerged pumps, but is the temp of 81.4 causing any problems??

Not a huge problem, though I would hope to run the tank slightly lower to provide for a margin of error should one pump begin to overheat. Also this is without the lights on, but when I did run a test with the lights (all T5) there was only a 0.1 increase after 4 hours. I would prefer to run slightly under 80 so that the fans only kick on at that threshold.


Just as an update, I have been working to isolate if any one pump was a larger heat source than others by turning off one at a time and watching temps. So far I have tested all but the Eheim return since I did not have another pump available to keep up the return. The below listed temps were taken after 3 hours of turning off 1 of the 5 pumps. Between each test I had allowed all pumps to run for 2 hours to bring the tank back to 81.4 degrees.
All pumps on = 81.4
Tunze off = 81.4
WM reactor off = 81.4
Vertex skimmer off = 81.3
Dart CL = 80.1
Eheim: not tested

This shows that the Vertex only contributes a 0.1 degree increase while the dart alone added 1.4 degrees. I had thought that the results would have shown the opposite. The only other source now is the Eheim which I will need to find a surrogate to test with or simply going with an external return pump. Another test I kicked off this morning is to throttle back the Dart slightly which dropped the wattage from 144w to 135w to see if the wattage drop alone can be used to regulate temperature. I should have a result by the end of day.

It should be noted that throughout all tests the fans and exhaust were left on continuously and evaporation remained steady at 3 gallons per day. The house/room temp was also kept at a constant. I live in Southern California where we have been under very low humidity (fire watches) for the past week so I believe I have my environment as controlled as can be expected.

[James77]

Im suprised the Dart was adding that much heat. Where do you keep the Dart pump?

[Kenfuzed]

The Dart is less than 2 feet to the side of the tank and elevated to the same level to reduce head pressure on the return side. It is fed by a 2" flex-pvc lines coming from 2 intakes drilled into the back. The intake is also a fairly straight pass without any harsh elbows, other than those coming out of the back of the tank. The output is 1-1/2" flex feeding 2 drilled outlets. The pump itself is only slightly warm to the touch.

[Kenfuzed]

UPDATE: after throttling back the Dart approx 1/4 to around 137w the tank temp settled in around 80.1 degrees. Still not ideal because it does not allow any room for temp spikes or the ability to turn off fans for any length of time. Next is to look at the Eheim. It already has a new impeller so I don't think there is anything wrong with it, other than being a 68w heat source sitting in the water.

[Pyrrhus]

just an FYI, there is absolutely no need to elevate a CL pump, there is no static head pressure in a CL. You could easily relocate that pump, and while it wont help your heat issue, it may help to clean up the overall setup.

On the heat issue, what is so magical about 80 degrees? Just raise the threshold you use for fans, etc to around 81.

The specific temperature matters very very little as long as you maintain it in the acceptable range and within a certain fluctuation range.

In my experience, when you maintain a very tight temperature range in your tank (+/- .5f) the corals become more susceptible to small changes in the temperature of the tank and even a degree or two of change can cause huge issues. Because of this I generally recommend a daily temperature swing of 2-3 degrees, no more, no less. In the past I have had tanks hit 89.4 degrees with zero losses, color took a hit, but all the animals survived, I attribute this to the higher base temp and the daily fluctuation better preparing the animals for thermal shock.

[unhpian]

Originally posted by PowermanKW
You basically have a 175 watt heater on continuously.

Don't mean to pick on you specifically - but that is dead wrong - but I see it said on here frequently, so you are far from the first person to believe it

The wattage a pump draws is the total amount of ENERGY it is consuming - and NOT the amount of heat it generates. In fact, if all of that energy were going into heating the tank (i.e., as a 175 watt heater), than the impeller wouldn't spin, and the pump wouldn't work - because all the energy is being used to "heat" the tank.

Pumps DO create heat - but it is a small fraction of the total amount of energy used.

If you want to find out the amount of heat produced by a pump, it all depends on its efficiency. A pump that is 80% efficient will use 80% of the electricity consumed to perform work (i.e., pump water) and 20% to produce noise, vibration, or heat. Since I've never seen an efficiency rating on aquarium pump, the best way to approximate it would be to do some fluid mechanics and find out the amount of work required to accomplish your flow rate - convert it energy units (i.e., watts) and subtract that from your actual usage via the Killawatt. Voila, an approximation of the amount of energy entering the aquarium as heat.

The same thing goes for lighting - a 175 watt MH bulb does not add 175 watts of heat to a tank. The only thing that will add 175 watts of heat to a tank is a 175 watt heater.

[unhpian]

Originally posted by mick243
any pump that is submerged will add its wattage to the tank as heat - ie, a 100w pump will add 100w of heat to the tank - some directtly as heat from the motor windings, the rest as kinetic energy imparted to the water which through friction ends up as heat.

if the pump is not submerged, this changes as some of its motor heat is lost to the air.

Again - wrong. A 100 watt pump will add 100 watts of ENERGY to the water - but most of it is as kinetic, and NOT heat.

[Pyrrhus]

Originally posted by unhpian
Again - wrong. A 100 watt pump will add 100 watts of ENERGY to the water - but most of it is as kinetic, and NOT heat.

And kinetic energy is lost to friction creating heat. There is no way around it, energy in=energy out in one form or another.

[Kenfuzed]

Originally posted by Pyrrhus
just an FYI, there is absolutely no need to elevate a CL pump, there is no static head pressure in a CL. You could easily relocate that pump, and while it wont help your heat issue, it may help to clean up the overall setup.

On the heat issue, what is so magical about 80 degrees? Just raise the threshold you use for fans, etc to around 81.

The specific temperature matters very very little as long as you maintain it in the acceptable range and within a certain fluctuation range.

In my experience, when you maintain a very tight temperature range in your tank (+/- .5f) the corals become more susceptible to small changes in the temperature of the tank and even a degree or two of change can cause huge issues. Because of this I generally recommend a daily temperature swing of 2-3 degrees, no more, no less. In the past I have had tanks hit 89.4 degrees with zero losses, color took a hit, but all the animals survived, I attribute this to the higher base temp and the daily fluctuation better preparing the animals for thermal shock.

The elevated pump was done more for convenience than anything else. The tank back shown in the picture is what you face when standing in that room (12x12 fish room/office) so placing the pump on the floor directly behind or on the floor below (in front of the sump) would have been in the way when placing a step ladder or other service needs to the tank and sump. Did I mention the tank sits on a stand I built 45" tall? Having the pump off to one side was the best option, and since I already had a small cabinet there it just made sense to place it on top. If it doesn't help reduce any head having to pump up 2 feet (elevated) as opposed to almost 5 feet if placed on the floor then no harm no foul. Pictures really do not depict how this set up is situated in this room. The pump actually sits inside the former closet that I removed the doors from.

Regarding temperature, I have been keeping tanks for 10 years and have always maintained temps at or near 79-80 with very little swing. I currently use an RK2 controller on my other tank that operates fans and heater to keep the temperatures near constant and will have a similar set up on this tank. I agree that stability is far more important than actual temperature but my comfort zone has always been 79 with 80 being the max and 78 the minimum. My current controller is set to turn on the heater at 78.2 and the fans at 79.7, while beginning to turning off lights and various pumps if temps exceed 80.5... which has only occurred once when a skimmer pump began to seize. I love automation

[James77]

Originally posted by unhpian
Again - wrong. A 100 watt pump will add 100 watts of ENERGY to the water - but most of it is as kinetic, and NOT heat.

Then the energy that is used to move the water just magically dissapears is what you are saying?

Originally posted by Pyrrhus
And kinetic energy is lost to friction creating heat. There is no way around it, energy in=energy out in one form or another.

This is correct.

[d0ughb0y]

Originally posted by Kenfuzed
The elevated pump was done more for convenience than anything else.

I think you did mention you elevated it to reduce head pressure.

Originally posted by Kenfuzed
The Dart is less than 2 feet to the side of the tank and elevated to the same level to reduce head pressure on the return side.

[Kenfuzed]

Originally posted by d0ughb0y
I think you did mention you elevated it to reduce head pressure.

Yes, but the other reason was based on convenience (not originally mentioned), so the intention was to kill 2 birds with one stone. It still seems to me that despite being a CL that there would be increased loss by placing the pump on the floor due to the additional length of pipe required to return to the tank, though its probably minimal. I'm not real interested in fluid dynamics or how much is decreased or not, I just want things to work. All I know is with the current CL configuration I've had to throttle back the output by approx 1/4 - or from a full flow that draws 144 watts to one that only draws 137w. This allowed the tank temp to settle around 80.1 without increasing my electrical usage by means of more (loud) fans. I will still be adding one more small fan to move more air between the lighting and water surface so any additional cooling there will simply allow the controller to cycle the fans rather than have them run continuously.

[unhpian]

Originally posted by James77
Then the energy that is used to move the water just magically dissapears is what you are saying?



This is correct.

No, the energy is consumed overcoming gravity and by friction.

It's the law of conservation of energy - You can't perform work (i.e., move water) and not expect some energy to be consumed in the process.

Think of it this way -

Total Energy Consumption = Work done by moving water + Frictional Losses (heat and degradation of tubing) + Sound Energy + Vibrational Energy + Internal Pump Friction (Heat, degradation of windings/impeller

If the heat produced is equal to the total energy consumption, than no work can be done because the energy has already been consumed.

Yes I agree that moving water causes friction which creates heat, but it's no where near the the total energy consumption of the pump.

[kmu]

I has an eheim in mind for my next set up but if its the culprit for alot of extra heat added to the tank i better look somewhere else.

What aré some energy efficient pumps to use for a submerged return pump?

[James77]

Originally posted by unhpian

It's the law of conservation of energy - You can't perform work (i.e., move water) and not expect some energy to be consumed in the process.

Energy is not consumed, but it can change form. Some of the energy may be converted by the pump to kinetic energy, but that will go to heat from friction.

Here is the Law of Conservation of Energy:
http://en.wikipedia.org/wiki/Conservation_of_energy

The law of conservation of energy states that the total amount of energy in a closed system remains constant. A consequence of this law is that energy cannot be created nor destroyed. The only thing that can happen with energy in a closed system is that it can change form....

Originally posted by unhpian
Work done by moving water + Frictional Losses (heat and degradation of tubing) + Sound Energy + Vibrational Energy + Internal Pump Friction (Heat, degradation of windings/impeller

Sound and vibration will go to heat also. The pump pulls a certain amount of energy. It converts(not consumes) some of that energy to moving water, kinetic energy. That kinetic energy will go back to heat, the sound will back to heat, vibration to heat. Energy can not be destroyed.

[James77]

Originally posted by kmu
I has an eheim in mind for my next set up but if its the culprit for alot of extra heat added to the tank i better look somewhere else.

What aré some energy efficient pumps to use for a submerged return pump?

It would depend on what GPH you are needing. Most of the more efficient submersibles don't do too well against head pressure.

[Freds]

To answer your question it's most likely the sedra. They are very inefficient pumps and thus are known to heat as they pump. Eheims are far more efficient and IMO are the best of the submersible pumps. If you were to replace the sedra or take it offline for a day you should see a temp drop.

[James77]

Originally posted by Freds
To answer your question it's most likely the sedra. They are very inefficient pumps and thus are known to heat as they pump. Eheims are far more efficient and IMO are the best of the submersible pumps. If you were to replace the sedra or take it offline for a day you should see a temp drop.

He did already, and the temp only dropped a tenth of a degree. Most of his heat is coming from the Dart pump.

[PowermanKW]

Originally posted by unhpian
Don't mean to pick on you specifically - but that is dead wrong - but I see it said on here frequently, so you are far from the first person to believe it

The wattage a pump draws is the total amount of ENERGY it is consuming - and NOT the amount of heat it generates. In fact, if all of that energy were going into heating the tank (i.e., as a 175 watt heater), than the impeller wouldn't spin, and the pump wouldn't work - because all the energy is being used to "heat" the tank.

Pumps DO create heat - but it is a small fraction of the total amount of energy used.

If you want to find out the amount of heat produced by a pump, it all depends on its efficiency. A pump that is 80% efficient will use 80% of the electricity consumed to perform work (i.e., pump water) and 20% to produce noise, vibration, or heat. Since I've never seen an efficiency rating on aquarium pump, the best way to approximate it would be to do some fluid mechanics and find out the amount of work required to accomplish your flow rate - convert it energy units (i.e., watts) and subtract that from your actual usage via the Killawatt. Voila, an approximation of the amount of energy entering the aquarium as heat.

The same thing goes for lighting - a 175 watt MH bulb does not add 175 watts of heat to a tank. The only thing that will add 175 watts of heat to a tank is a 175 watt heater.

You might want to dust off the physics books. Watts is power, not energy. Power is energy over time. If a pump consumes 100w of power and it is in the fluid it is pumping, 100w of energy is directly expended in the tank.

Energy can't be destroyed, only converted. It's a broad brush here, but about 95% of all motion energy dissipates to heat energy.

The by product of the winding moving the magnets drawing current to do work to move the water and cause friction.... all dissipates to heat. That 100w is a measure of energy consumed, and therefore a measure of the energy added to the system. It does not magically disappear from the system. As was said earlier, energy in, energy out.

And power factor of the pump has nothing to do with it. Apparent power infact is worse. Aquarium pumps only have a 50% PF so all the. That other 50% is directly lost as heat due to inefficiencies of true power and power factor.

[PowermanKW]

Originally posted by unhpian
No, the energy is consumed overcoming gravity and by friction.

It's the law of conservation of energy - You can't perform work (i.e., move water) and not expect some energy to be consumed in the process.

Think of it this way -



If the heat produced is equal to the total energy consumption, than no work can be done because the energy has already been consumed.

Wrong, heat is produced from the work imparted to the system that was done by the consumption of power and the addition of energy to the system. Heat is the byproduct of work. 175w worth.