return pump

[bluetang22]

what is pros and cons on internal or external pump. i plan to purchase Iwaki MD40RLXT, thanks

[TimH07]

i'd have to say that external anything always have a chance to leak or worse, an internal runs a risk of shock but you should have that worked out running a reef anyhow with a gcfi outlet and grounding probes.

if your return will be in the sump below the tank it would be better, in the event of a leak it would just drip into the sump no problem.

my opinion, get internal.

also internals wont overheat, externals might if they fail

[Doodaa]

Some people worry about the heat and internal pumps add to their system. I'd like an internal for that reason, but there isn't decent priced ones that give me the flow I want.

Externals in general are more powerful. I'd almost argue that they are easier to dismantle from the system to clean. They don't take away from your tanks footprint either...more water volume and more space to put other things.

Internals are probably more quiet...I'm just guessing. They could be a little easier to plumb into the system. A lot depends on that though.

As far as reliability goes...I think it boils down to "You get what you pay for", but maintenance goes a long way too. I don't think one really outshines the other. It all depends on how it fits into your system and what you want.

[kevinpo]

I run many of each type and it's really about the application (what would you like the pump to do?). Some things to consider are, flow rate, flow curve at head, power consumption, and noise level.
Some of the external pumps that are low rpm, low power, low heat, totally silent, and high flow (3,000-5,000gph) make poor return pumps because of their pump flow curves. They are best suited for closed loop or recirculating skimmer type pumps.
High rpm, high amp, pumps are louder and produce more heat but many of them can pump 20' and still produce impressive flow rates.
Internal pumps that produce 2,000gph+ can be a significant source of added heat but depending on your geographic or tank location this could either be a positive or negative thing.
With so many pump choices today I recommend careful consideration/research before buying a pump.

Regards,
Kevin