ext pump with lowest heat transfer?

[VisionQuest27]

So i am trying to decide on the right external pump for a 240g FOWLR. The biggest thing i am looking for is a pump with the least heat transfer. Right now the tank is running with 2 CAP 5000's, and i think that they are adding some serious heat to the tank. Im not sure on the exact head pressure it would need to handle, but there are 2 returns on opposite sides of the tank, and it would also have to run to a chiller that is probably about 5 feet away through the wall behind the tank. A few of the pumps i am looking at are PanWorld, Sequence, or maybe Gen-x. I am not totally decided on which model of each pump i might use...so im open to suggestions and any input. Thanks alot guys....

[smcdonn]

Japanese Motor Iwakis are great pumps. I added one to my 75 gallon with almost no noticable increase in temperature.

[VisionQuest27]

Thanks for the reply...Iwaki's were another pump i was considering. Anybody else have experiance with the other pumps i listed? Would love to hear some feedback from you!

[LegoZ81]

I have a Panworld 100PX-MD40R, I don't know the heat transfer rate. But it's been great as a return for my basement sump.
If you have a good way for me to test lmk.

[VisionQuest27]

The only way i know how to tell is if you notice an increase in temp after installing the pump.