I went down to the local hydroponic store and talked to one of the clerks about purchasing a new pump for an aquaponic system. He suggested a Mag-Drive pump (more expensive) because it puts less heat in the tank then a conventional pump. I had never heard that before. Was the guy just trying to "pump" me for more money or is it legit? Thoughts?
Well yes, it would make sense. Since their is no shaft mechanically tying the pump to the motor...there is much less friction and probably little or no heat transfer from the motor...which would mean much less heat in the water.
I use two of them (and have a third one as a spare).
There are probably at least a couple more things that may be advantageous, but they seem kind of on the fringes of "likely to ever come into play"...Though I guess that would depend on where and how you run your system.
For one, they seem better designed to handle being turned on and off frequently (like in a timed flood and drain scenario)...and secondly, since the motor is magnetically coupled, rather than mechanically...it can 'easily' be "de-coupled" when over-loaded, with no damage being done to the pump.
At any rate, I'm of the opinion that they are worth the extra money, but that's just my 2 cents...
What sold me on mag-drive pumps is that they are self-contained, so they won't leak any harmful oils into your system.
With the amount of amount of water passing through, heat generated from the pump motor would be minimal. Any time you compress anything you concentrate heat. Water in essentially incompressible so there would very little heat.
All of the pumps have a seal that prevents water from getting into the motor. Water and electricity, especially the kind of water we are using in an aquaponic system, aren't good friends. It tends to short out a motor.
The advantage of a mag driven pump is, if the pump stalls from debris overload, it won't stall the motor and cause the motor to fail.