how much heat does a submerged return pump add?

[shamrock]

hi

i came across a few threads/information about this. does anyone know how much heat a submerged return pump adds vs an external pump? i live in Australia, and, except for winter, ambient heating will usually not be an issue (but i will of course need to use a heater).

any pearls of wisdom would be appreciated! would it be worth doing an external setup rather than submerged, or is the difference negligible and not worth the extra plumbing?

thanks
sk

 

[ReefRondo]

I’ve never noticed a difference at all. I guess the size of the tank would be the main consideration. Smaller the tank the more that pump would potentially heat the water.

 

[lapin]

Big pump - big heat.
Small pump - little heat

 

[Johnd651]

I would guess that you can probably solve based on pump wattage. Since 1 watt is 3.41 btu/hr, you can convert to get a rough idea of heat being put off... since there is not much else going on in a pump. But temperature rise will probably depend on volume if you consider the fact that liquid cooling (pump in water) means you're using the water like a large heat sink.

 

[Roush427R]

It depends on the pump, as well. Some pumps run warmer than others.

 

[shamrock]

thank for your input. i don't think it would be worth the hassle of external pump in my setup.

 

[mfinn]

I used to use Poseidon/Velocity pumps. These were the very first truly silent pumps that I saw in the hobby.
They were known for running very warm. A single P4 ( models #2, #3,#4) could add 4-5 degrees to a 100 gallon tank.
They were a external only pump
What I did to be able to use them was to get a small clip-on fan ( 6") and have it blowing on it.
The fan alone would do the trick.

 

[Snoopy 67]

I have had pumps add 5-10 degrees to a 250 gallon tank run internally.
I now run a Red Dragon pump with only a degree or 2 difference.

 

[ca1ore]

A submerged pump will transfer all of its wattage to the tank water as heat. An external pump will transfer some of it’s wattage to the tank water as heat and some to the air. Depending on pump and stand design, this percentage will vary.

 

[bryanfuel]

I have a Rio1400 in my 29 Biocube and it keeps my tank at ~72F at night with no heater even when my apartment is ~69F

 

[Blue Spot Octopus]

Use the hot pumps during the winter and the DC pumps during the summer.

 

[Quietman]

I've always used Hamza's Reef Calculators to estimate heating and chiller needs.

Paraphrasing from that source: 100% of wattage of submerged internal pump is converted to heat energy (even the water motion is dissipated as friction (heat)). External pumps vary - 15-25% of wattage unless they are water cooled which bumps it up to 80%.

https://www.hamzasreef.com/

 

[KrisReef]

I put a 3000 gallon per hour external pump on a 125 gallon tank and filled it with cold tap water to tune the overflow. The tank went up to 90+F in 12 hours just from water movement as there was no other equipment in the system. It was 68F outside and we were not running any room heater.

Get the lowest watt pump you can to move the amount of water needed in your system. This is the smartest way to remove (excess) heat from the equation.