Internal vs External return pump

canesfan44 · 10/20/2009, 11:35 PM

I'm going to be setting up a 90g SPS tank and want to know if I should use an internal or external return pump. My main question would be heat. I've never used an external pump and was wondering if running an external pump would generate more heat than an internal. I have an ehiem1262 that I would use internally, because someone told me that they run pretty hot externally. Any help will be greatly appreciated.

Mr. Brooks · 10/21/2009, 03:09 AM

Use it internally. Less mess. They add heat either way.

James77 · 10/21/2009, 06:56 AM

Some of the larger fan cooled pumps, such as Reeflo/Sequence, add less heat. Water cooled pumps like eheim will add the same heat whether external or internal.

Freds · 10/21/2009, 04:35 PM

!!??
So assuming you have a Brand A internal pump that uses 65 watts and you have a Brand B external pump (iwaki clone) that uses 65 watts and assuming they have the same efficiency they would heat the water just the same?

Wouldn't the external nature of the pump allow for some of the heat to leave into the air rather than into the water? In the scenario above the Brand B pump is fan cooled so wouldn't that mean that much of the heat would leave into the air?

I really don't know I'm asking

I would assume that if you used Brand A internally and then tried Brand A externally you would find that external would be cooler as some of it would dissipate into the air. Maybe a negligible amount?

Anyone tried this?

Hawkdl2 · 10/21/2009, 05:04 PM

It depends on how you are setting up your tank. If the pump is the primary source of water movement and turnover in the tank and there's lots of plumbing causing lots of head loss, then you will probably end up with a larger external pump. If you plan on incorporating powerheads such as Tunze or Vortech as a principle source of movement and the return pump is largely to keep water moving through a sump/skimmer/refugium, than an internal pump may be the preferred route since it will eliminate leakage worries and reduce the space require din your stand. The smaller Ehiem type of pumps are great for this, don't use much wattage and therefore don't add a lot of heat to the system.

For my current 90g I went with the internal Eheim and two Vortechs. compared to my previous 150 with a Dolphin external, OM 4 way and lots of plumbing, I find my new tank a whole lot less complicated. For a bigger tank, I might go external and the Vortech, eliminating some of the plumbing.

James77 · 10/21/2009, 05:22 PM

Quote:

Originally Posted by Freds

!!??
I would assume that if you used Brand A internally and then tried Brand A externally you would find that external would be cooler as some of it would dissipate into the air. Maybe a negligible amount?

Anyone tried this?

Someone did a test of an eheim and a 5 gallon bucket, he measured the temp with the pump inside and outside the bucket. There was very little difference in temp between each setup. IIRC, with the pump outside the bucket it was even warmer.

James77 · 10/21/2009, 05:27 PM

Found the test, it was a mag12, not an eheim.

Quote:

Originally Posted by 8BALL_99

Well I didn't get around to testing till last night.. I decided to replace a vanity top in our guest bath.. Well that turned into getting a larger Vanity and top.. Then that turned into moving the water and drain lines.. Well then I had to patch the sheetrock where the old lines were.. Then I figured since I had my Sheetrock tools out I might as well go over some of the not so great seams in the room.. So then of course we had to paint the entire room a new color...Sigh so my 30 min job of a new vanity top turned into a weekend Bathroom remodel lol..Anyway

I tested a Mag12 both External and Internal. The test was done in a little less then 4 gallons of saltwater in a 5 gallon bucket. Also my Pump wattage might be a little on the high side.. My watt meter reads a little high.. It reads a constant wattage though..

External Test-------------------------------Internal Test
Saltwater @ 1.025------------------------Saltwater @ 1.025

Start 7:07pm-------------------------------Start 12:38am
Water Temp 75.7---------------------------Water Temp 75.5
Pump Case Temp 79-----------------------Room 75
Room Temp 75------------------------------Pump Wattage 190
Pump Wattage 191Watts

8:07pm-----------------------------------------1:40am
Water Temp 81.9-----------------------------Water Temp 82
Pump Case Temp 98-------------------------Room 75
Room 75----------------------------------------Pump Wattage 192
Pump Wattage 194

9:07pm-----------------------------------------2:40am
Water Temp 86.6-----------------------------Water Temp 86.1
Pump Case Temp103-------------------------Room 75
Room 75-----------------------------------------Pump Wattage 192-193
Pump Wattage 194

10:07pm----------------------------------------3:40am
Water Temp 90.1------------------------------Water Temp 88.9
Pump Case Temp 104-------------------------Room 75
Room 75------------------------------------------Pump Wattage 194
Pump Wattage 194

11:07pm
Water Temp 92.7
Pump Case Temp 105
Room 75
Pump Wattage 197

12:07am
Water Temp 93.5
Pump Case Temp 105
Room 75
Pump Wattage 196

I didnt' bother testing more then 3 hours on the Internal It was getting late and as you can see pretty much The Exact same tempiture increase anyway.. Only difference is that the pump seemed to pull a few more watts External as it heated up faster..

I still plan on Testing a Eheim but I have a feeling the results will be the same.. IMO/IME mounting a Water cooled Internal pump as a External pump doesn't do anything but make it louder...

Will

canesfan44 · 10/21/2009, 07:50 PM

Thanks James77 for showing that little experiement, I wish he also tried using an equivalent external only pump, like an Iwaki(Pan-World, etc), because it might be possible that an Iwaki(blueline, reeflo, etc) might create less heat than an equivalent internal. For example, would an Iwaki MD30RLXT heat the water more or less than an eheim1262(used internally). I already have an eheim1262 but if an Iwaki(or some other ext pump) heats the water less than the Eheim(the only pressure/head loss will be the 5-6' from the fuge to the tank and an eductor), I would rather use the external.

James77 · 10/21/2009, 07:54 PM

If the Iwaki is fan cooled, then it will add alot less heat than a pump that is both submersible and external. I ran a Sequence Tarpon, about 160 watts external fan cooled, and it added almost no heat to my tank. I switched to a Velocity, external water cooled fanless pump, and it kicked my temp up by a good 2 degrees.

d2mini · 10/21/2009, 08:02 PM

I find that an external pump is just easier to deal with for maintenance and such. And it's one less thing in the sump.
I had external on my last tank, internal on my current one and I'll be doing external on my next tank.

10/20/2009, 11:35 PM	#1
canesfan44 Registered Member Join Date: Jan 2005 Location: S Florida Posts: 1,728	Internal vs External return pump I'm going to be setting up a 90g SPS tank and want to know if I should use an internal or external return pump. My main question would be heat. I've never used an external pump and was wondering if running an external pump would generate more heat than an internal. I have an ehiem1262 that I would use internally, because someone told me that they run pretty hot externally. Any help will be greatly appreciated.

10/21/2009, 06:56 AM	#3
James77 Registered Member Join Date: Aug 2005 Location: Rhode Island Posts: 8,158	Some of the larger fan cooled pumps, such as Reeflo/Sequence, add less heat. Water cooled pumps like eheim will add the same heat whether external or internal. __________________ Jim Current Tank Info: 120g Mixed Reef and 75g Freshwater

10/21/2009, 05:04 PM	#5
Hawkdl2 Mad Scientist Join Date: Jun 2001 Location: Claremont, Ca Posts: 2,233	It depends on how you are setting up your tank. If the pump is the primary source of water movement and turnover in the tank and there's lots of plumbing causing lots of head loss, then you will probably end up with a larger external pump. If you plan on incorporating powerheads such as Tunze or Vortech as a principle source of movement and the return pump is largely to keep water moving through a sump/skimmer/refugium, than an internal pump may be the preferred route since it will eliminate leakage worries and reduce the space require din your stand. The smaller Ehiem type of pumps are great for this, don't use much wattage and therefore don't add a lot of heat to the system. For my current 90g I went with the internal Eheim and two Vortechs. compared to my previous 150 with a Dolphin external, OM 4 way and lots of plumbing, I find my new tank a whole lot less complicated. For a bigger tank, I might go external and the Vortech, eliminating some of the plumbing. __________________ Larry Current Tank Info: 120g mixed reef.

10/21/2009, 07:54 PM	#9
James77 Registered Member Join Date: Aug 2005 Location: Rhode Island Posts: 8,158	If the Iwaki is fan cooled, then it will add alot less heat than a pump that is both submersible and external. I ran a Sequence Tarpon, about 160 watts external fan cooled, and it added almost no heat to my tank. I switched to a Velocity, external water cooled fanless pump, and it kicked my temp up by a good 2 degrees. __________________ Jim Current Tank Info: 120g Mixed Reef and 75g Freshwater

10/21/2009, 03:09 AM	#2
Mr. Brooks MASVC Member Join Date: Apr 2007 Location: Simi Valley, CA Posts: 3,477	Use it internally. Less mess. They add heat either way.

10/21/2009, 04:35 PM	#4
Freds Registered Member Join Date: Mar 2006 Location: Brooklyn, NY Posts: 229	!!?? So assuming you have a Brand A internal pump that uses 65 watts and you have a Brand B external pump (iwaki clone) that uses 65 watts and assuming they have the same efficiency they would heat the water just the same? Wouldn't the external nature of the pump allow for some of the heat to leave into the air rather than into the water? In the scenario above the Brand B pump is fan cooled so wouldn't that mean that much of the heat would leave into the air? I really don't know I'm asking I would assume that if you used Brand A internally and then tried Brand A externally you would find that external would be cooler as some of it would dissipate into the air. Maybe a negligible amount? Anyone tried this?

10/21/2009, 07:50 PM	#8
canesfan44 Registered Member Join Date: Jan 2005 Location: S Florida Posts: 1,728	Thanks James77 for showing that little experiement, I wish he also tried using an equivalent external only pump, like an Iwaki(Pan-World, etc), because it might be possible that an Iwaki(blueline, reeflo, etc) might create less heat than an equivalent internal. For example, would an Iwaki MD30RLXT heat the water more or less than an eheim1262(used internally). I already have an eheim1262 but if an Iwaki(or some other ext pump) heats the water less than the Eheim(the only pressure/head loss will be the 5-6' from the fuge to the tank and an eductor), I would rather use the external.

10/21/2009, 08:02 PM	#10
d2mini Registered Member Join Date: Nov 2008 Location: Houston, TX Posts: 10,344	I find that an external pump is just easier to deal with for maintenance and such. And it's one less thing in the sump. I had external on my last tank, internal on my current one and I'll be doing external on my next tank.