Pump verses Heater

[Guest thefishman65]

It was suggested to me that I don't have enough turn over in my tank. 75 gallon with a mag 5 return so maybe 270. I do have 2 korallia 1400 in tank on alternating cycles. Opinios welcome on this too.

 

So I am considering a new pump. I was also told that mag are not very efficient. Gee when I got it 20 years ago it was pretty good. I also run LED lighting.

 

So my question. Does it matter if I buy a more efficient pump? If one pump is 50 watts and another is 100 (assuming all else is the same). Won't that just mean my heater runs less? Or is the heater a much more efficient way of keeping the temperature correct?

 

Does 50 watt motor + 50 watt heater = 100 watt motor?

 

If it is better to have an efficient motor I also welcome opinions for those.

 

Thanks

[firecrackerbob]

Hmm, I had to think about what you were asking for a minute... but If I understand your Q correctly, I think you are trying to compare apples and oranges. When you are looking at a pump, I think most people are looking at how much water gets moved per wattage. So comparing say a 50W pump that moves 300gph vs a 100W pump that moves 800gph lets say. While pumps obviously produce heat as well, most of the energy (I hope) goes into water momentum, not frictional losses, which produces the heat. Heaters on the other hand utilize their wattage to heat a metal coil which raises water temp.

So, to your original Q, 50W heater+50WPump does not equal a 100W heater

[Origami]

Does 50 watt motor + 50 watt heater = 100 watt motor?

No, but heat is heat. If the pump is inefficient, then losses are primarily to heat and to turbulence. If 50% of the energy is going to heat, then it's like having a 50W heater running in your tank 100% of the time. By comparison, a 50W heater in your tank has a thermostat which controls when it's on and when it's not. Your return pump will be on all of the time, so the comparison's not quite the same.

 

The "good" (useful) part of the power that a pump is consuming is going to lift a certain volume of water up some distance (which takes energy), thereby raising it's potential energy. That energy divided by the total energy of the pump consumed in that time will establish your efficiency of the pump. Hopefully the 100W pump that you're eluding to is pumping more water than the 50W pump. If it's not, the comparison is a fair one, if you neglect losses due to turbulence.

[Guest thefishman65]

Sorry, yes assuming both end up pumping 300 GPH at 4 feet (same piping - what turbulence?). I realize you will also probable never find two pump that meet the requirements, but it is easier to think about. I also should have stated something like the heater runs 100% (not a good idea I realize) and the water stays at 75 degrees.

 

So in my case I don't need an efficient pump. My criteria should be (if I decide on a new one)

1. Quiet
2. Reliable
3. ease of cleaning
4. any other recommendations