Mag-7 heat dissipation
 

I just picked up a pair of Danner Mag-7 water pumps. I'm planning
on using them in parallel redundancy on a 180G tank I'm setting up.

To test them I placed them in a 5 gallon bucket filled with water
and turned them on overnight. The next morning, to my horror, when
I placed my hand in the bucket to feel the water flow I just about
got burned. The water was VERY hot, well over 100 degrees.

Does this sound right?

I know they're supposed to dissipate SOME heat into the water when used
submerged. And I also know that the problem won't be so bad in a 180G tank
compared to a 5G bucket.

BUT THAT WATER WAS HOT!

I'm starting to worry about poached fish.

ADVthaAnksNCE

Joel M. Baldwin wrote:

To test them I placed them in a 5 gallon bucket filled with water
and turned them on overnight. The next morning, to my horror, when
I placed my hand in the bucket to feel the water flow I just about
got burned. The water was VERY hot, well over 100 degrees.



Well, look at it this way. On the nameplate it should say how many watts
of power they use. Think about heaters that use that many watts. Surely
that's too much to have on ALL the time in a five gallon tank. But is
thatt number a fair amount below the amount of thermostat-controlled
heating you have in the tank? If so, then I'd not worry, since the heat
effect is going to be like that of x-watt heaters (where x is what the
two pumps use) turned on all the time. I expect we're talking 60 watts
here, and I expect that a 60-watt, alone in that tank, would never turn
off on its own.

So really, don't sweat it. Your heaters might turn on a little less.
That's it :-)

--jjoe

Jesse Joe wrote in news:d4rbo9$mjm$1@news-
int2.gatech.edu:

Joel M. Baldwin wrote:

To test them I placed them in a 5 gallon bucket filled with water
and turned them on overnight. The next morning, to my horror, when
I placed my hand in the bucket to feel the water flow I just about
got burned. The water was VERY hot, well over 100 degrees.


Well, look at it this way. On the nameplate it should say how many watts
of power they use. Think about heaters that use that many watts. Surely
that's too much to have on ALL the time in a five gallon tank. But is
thatt number a fair amount below the amount of thermostat-controlled
heating you have in the tank? If so, then I'd not worry, since the heat
effect is going to be like that of x-watt heaters (where x is what the
two pumps use) turned on all the time. I expect we're talking 60 watts
here, and I expect that a 60-watt, alone in that tank, would never turn
off on its own.

So really, don't sweat it. Your heaters might turn on a little less.
That's it :-)

--jjoe

Logical and reassuring, however I would have expected that a large portion
of that 60watts to be expressed as mechanical energy in the water movment,
not as thermal energy into the water.

Your explaination of needing less heater wattage as a result is useful
during the winter when the house is cold and the water needs to be heated,
but during the summer my house will be quite warm and a heater won't be
on very often. I may end up with a tank that is too hot.

I'm starting to think I should mount them inline rather than submerged.
And make sure that the sump area is WELL ventilated.

"Joel M. Baldwin" wrote:
Logical and reassuring, however I would have expected that a large portion
of that 60watts to be expressed as mechanical energy in the water movment,
not as thermal energy into the water.

Most of the power *does* initially get used to move the water. However, the
same effects that result in the water movement being damped in the aquarium
(friction, etc.) ultimately result in most of the energy being converted to
randomized heat.

I have a few Danner mag drives that are usableas external or
submersible to ppower various filters etc on some tanks I keep
outside. In the summer time I run them as externals so they do not get
too much heat built up in the tanks, in the winter they run as
submersibles and helps keep the water warmer and heaters off longer.

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