What skimmer is preferred based on actual comparisons?

[gcarroll]

Originally posted by RichConley
gcarrol, thats not entirely true. THe problem here, is that theres only 2 products produced by the pump. Heat, and water movement. The water movement is reduced to heat by friction(if not, your water would move forever after you turned off pumps), so efficiency does not matter. Heat transfer from a submersible is directly proportional to wattage. When you start talking about externals, than efficiency is a concern, but not with a submersed pump.

I don't think so Rich. I look at it as 1 product, the work that the pump was designed for. That product is water movement, that is the work that the pump was designed to perform. Heat is not the work that the pump was designed to perform, therefore it is a byproduct of the pumps inefficiency to produce it's work.

When the byproduct of a pump is heat and that pump is in the water, that heat is a concern and will be transferred to the water. Heat transfer is not directly proportional to wattage because some motors are more efficient than others at doing their work. The heat produced by the movement of water is minor and will play a small role in a temperature rise. So minor that it is doubtful that our thermometers would ever pick it up.

[RichConley]

Originally posted by gcarroll
The heat produced by the movement of water is minor and will play a small role in a temperature rise. So minor that it is doubtful that our thermometers would ever pick it up.

Thats where you are wrong. The heat released by water when it comes to a stop (by friction) is the same as the heat(energy) required to get it to move with a perfectly efficient pump.


So lets say it takes 10w to get water to move x fast.

Pump A uses 20w to move water x fast. So 10W is store in the water as it moves. The pump produces 10w of straight up heat, and 10w is released from the water when it comes to a stop. 20W of heat.

Pump B is much more efficient, and moves water 1.5x. It only releases 5w of heat. THe problem is that the energy (kinetic) is stored in the water, and when the water comes to a stop, it'll release the 15w of energy as heat beacuse of friction.

Its simple conservation of energy.

[scottfarcuz]

So you are saying metal friction, and heat coming from the electricity being conducted is directly proportional to water friction?

[Paulairduck]

I dont agree that all pumps, the same wattage, produce the same amount of heat. They may all produce heat, but what we care about is the transfer of the heat to the water. There are many different types of plastics, insulations, that can be used to guard against heat transfer. Why are some pumps more noisy? Why is heat transfer increased toward a particular brand? You get what you pay for, and one of those things, though they may be secret, is engineering and design. All I know is that I ran a Gen-x pump, and it might as well call the pump a heater too, (COMBO). My eheim pump is awesome, my tank runs cooler, and no variable's have changed. Same wattage, and deffinitely a big diiference in heat transfer.

As far as the skimmer,I have used almost all the skimmers. CPR bak pak(first skimmer), ASM's are great for the money, Euro reef's are great, but same design as ASM, My MRC took up to much electricity, My octopus skimmer was worth every penny, great performer, now I have Deltec on the way, so we will see!!!!

[RichConley]

Originally posted by Paulairduck
They may all produce heat, but what we care about is the transfer of the heat to the water. There are many different types of plastics, insulations, that can be used to guard against heat transfer.

Insulation does not prevent heat transfer, it mearly slows it. When you insulate a pump, the pump gets hotter internally, and then starts transfering heat at the same rate as a non insulated pump. If this was not true, the pump would heat up and the metal inside would boil.

A more efficient pump at the same wattage will get you more water flow/pressure. it will not get you less heat. We can argue all day, but this is simple highschool physics. Its conservation of energy. If its going into the pump its either coming out as heat, or water movement, and all that water movement is being converted to heat.

[gcarroll]

Originally posted by scottfarcuz
So you are saying metal friction, and heat coming from the electricity being conducted is directly proportional to water friction?

Yes, that is what he is stating but if his statement is true it would only apply to the starting and stopping of the water. If you only turn the pump on, and never turn it off the water never stops moving and you only get half the heat. I wonder if those fools with pumps on wave timers no how much heat they are adding to their tank.

[RichConley]

Originally posted by gcarroll
Yes, that is what he is stating but if his statement is true it would only apply to the starting and stopping of the water. If you only turn the pump on, and never turn it off the water never stops moving and you only get half the heat. I wonder if those fools with pumps on wave timers no how much heat they are adding to their tank.

Thats not completely true. Well it is, pumps use way more electricity starting than they do running. A 20w rated pump may draw 50w at startup. (most likely around 30w)

As the pump is starting up, the energy being drawn is used to accelerate the water. Very little kinetic energy is lost to friction. As the water speeds up, more kinetic energy is lost to friction. After a couple seconds, you reach a steady state, where the energy going in (kinetic energy from pump) is the same as the energy going out (kinetic energy lost as heat due to friction.) That is why water velocity stays constant in your tank. If the pump was adding mroe energy than you were losing, your water would keep accelerating. if your pump was adding less, the water would slow down to a stop.

Once you reach that steady state, all energy being input to the system is mearly to maintain it, and is lost as heat.

[QtJenny19]

I thought this thread was based on the skimmers, not just the pumps they were attached to?

[manderx]

RichConley is right. it's basic thermodynamics. you're putting energy into the system, and it *all* has to go somewhere, remember 'can't be created or destroyed'? different pumps might move different amounts of water per watt (be more or less efficient at pumping water), but that consumed energy (which we can measure with a watt-meter) *has* to go somewhere. in the case of pumps, some goes to em radiation and the vast bulk goes to heat. whether it's heat generated in the pump, or heat generated when that water molecule hits a rock. if a submersible pump draws 50 watts, it's *exactly* the same as dropping a 50 watt heater in there and leaving it on 24/7.

it's slightly different with external pumps since they have the option of outputting heat to the atmosphere rather than the water. some are better at that than others.

[gcarroll]

Are you telling me that if I move 100 gallons of water at a rate of gallon per minute through a 1" pipe, it doesn't matter if it took 100 watt pump or a 1 watt to do the job, the water from the 100 watt pump will pack 100x more energy than the water moved by the 1 watt pump? I'm not so sure that is the case.

What if we took a pump that moved 100 gpm through a 1" pipe, using 100 watts. Would that "water" pack the same energy as the pump that moved 10 gpm through that same pipe using the same power?

I think you guys are leaving out the properties of the electric motors when making your statements

[manderx]

not really sure i understand what you are saying. water flowing through a pipe doesn't know how many watts it took to generate. it only knows how fast it's moving. this velocity (kinetic energy) is *all* eventually turned into heat within the system (friction when it hits a rock, and friction from rubbing against other water molecules). this heat + the heat generated by the inefficiencies in the pump (electrical resistance + friction of moving parts) will always equal the total wattage consumed by the pump.

so if i'm reading your example correctly, if you have 2 pumps of different wattages that are producing the exact same flow, then the difference in wattage will be heat generated within the pump. bear in mind that you cannot go by the labels on a pump as to the wattage drawn, you gotta measure it. ever look at a pump/wattage curve? notice how as flow goes down (from increasing head pressure) the wattage also goes down?

I think you guys are leaving out the properties of the electric motors when making your statements

what properties? they don't matter anyway. the whole entire issue is covered by the laws of thermodynamics. energy out = energy in. always.

[thirdchaos]

Manderx and RichConley are entirely correct. The work performed by two pumps of equal wattage result in the same heat output. The laws of physics do not care what type of materials are doing the work.

[Serioussnaps]

ASM G3 by far......unless you can afford a Deltec

[viggen]

interesting stuff I must say. However for us non-thermodynamics peeps..... it's kinda difficult to understand

But from what I gather it's similar to a turbo on a car. If I recall the thermodynamics people state the heat is what causes a turbo to spin & develop boost.

[gcarroll]

I'm gonna quit trying to understand it. It is what it is! Thanks guys. I guess it's all different when water is involved.

[UCanDoIt]

Originally posted by RichConley
45w vs 22w vs 22w. Theres your difference. (rated)

I stopped by my dealer this afternoon and the rating on the 3 skimmer's pump are as follows:
Octopus RPS1000 - 18w
Deltec AP600 - 20w
H&S A110-F2000 - 18w

Definitely the Octopus skimmer feels a lot warmer than the other 2 units. Don't know what causes the difference in heat transfer into the water.

Originally posted by QtJenny19
I thought this thread was based on the skimmers, not just the pumps they were attached to?

It's the pump that makes the skimmer. There's quite a few design items on a skimmer that optimizes it performance, but the pump with a well designed needlewheel impeller is so important. IMO and I'm no professional, if the German AquaBee pump or the Eheim could be put onto a well made EuroReef or Reef Octopus skimmer, they would perform so much better and transfer less heat back into the water.

[BLockamon]

To be honest, I don't think that the pump heat from an external skimmer is an issue. At most, maybe half the power is removed as heat, so we're talking 9-10 W. That's not going to affect the temperature of a tank...even a small one. We all have heaters in the tanks rated for 100-300W that run at least part of the time.

If you have problems with tank temperature from one of these skimmers, you probably need to add fans or a chiller anyway.

[JER-Z]

Originally posted by thirdchaos
Manderx and RichConley are entirely correct. The work performed by two pumps of equal wattage result in the same heat output. The laws of physics do not care what type of materials are doing the work.

everyone is oversimplifying a bit...kinetic energy also converts into other forms of energy, ie sound, electromagnetic waves, etc...

in otherwords, a pump that is more efficient will produce more kinetc energy, which is NOT all converted to heat by friction. Thus, less heat transfer.

Plus you have to factor in other things like surface agitation...The heat from friction loss will be lost into the air, not the water because of the difference in the coefficient of heat...

simpler terms.... a 50W heater does not = 50W pump

[RichConley]

JER-z, the amount converted to EM and sound is insignificant in comparison to what becomes heat.

[JER-Z]

Originally posted by RichConley
JER-z, the amount converted to EM and sound is insignificant in comparison to what becomes heat.

it's possible...but I would like a physics wizz to do it all up on paper to put the argument to rest.

The fact is when calculating heat produced by friction, one cannot simply disregard EM and sound if they want a true measurement.

[DrBDC]

It's probably easier to compare 2 pumps both pulling 20 watts (measured, not rated). That 20 watts is converted into something. Either impeller movement (water movement), heat, sound, etc. So if one moves 100 gph and the other only 75, there is 25 gph worth of energy that is converted into some other form of energy. Take your pick what kind. That is in addition to the energy lost in other forms from the first pump moving the 100 gph since it will have energy lost in other forms as well.