I've had the Mag pumps and currently have an Eheim as a sump workhorse. The Mag 24 I had put out a LOT of heat, use a LOT of power and was a LOT of loud. I didn't need a heater on my tank the whole time I was using the Mag 24, keeping the water temp at 76 degrees consistently in the winter, but summers were a challenge. My tank is in my dining room so it was very noticeable. The Eheims don't pump that much water quantity for a return pump for what they cost, but they are very reliable. I got an ATB Flowstar pump last summer in a group buy Tanglovers organized and the flow is less than the Mag I had (like 1500 gph at 5' head), but they are dead silent, use much less energy, and don't put off the heat. They can be use internally or externally, and it was a couple bucks well spent. The new Sicce pumps look good, too, but I haven't checked them out carefully. Tanglover's whole system after the addition of his new 520 gallon tank is run by the Flowstar pumps.