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If I am running an HoB filter to expose moving water to air, but the impeller is immersed, how does the air cooling compare to the addition of heat from the impeller? That is the fancy question.

The real question is, "Do I benefit from running an HoB in a heat wave, versus just sponge filters?"

This is not a rhetorical question! I am thinking about this because of my aquariums.

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Thanks, @lefty o

I was running two lights because I have more lights than tanks, but I removed one today. I thought about using two Nanos, but I went from two to one 15-24" unit. I am running my AC at 73°F in that room, but I am still getting Apex warnings of >80°F temperature. I am going to remove the HoB and see what happens.

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Hi, agreed with @lefty o. On my radio controlled planes, which use the same technology in the motor as the impeller of a filter (Magnets rotating a shaft). The motor of an airplane almost always gets a little warm regardless of the amount of airflow going over it.

Edited by FlyingFishKeeper
Misunderstood electric motors
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On 6/28/2021 at 9:08 PM, Streetwise said:

Thanks, @lefty o

I was running two lights because I have more lights than tanks, but I removed one today. I thought about using two Nanos, but I went from two to one 15-24" unit. I am running my AC at 73°F in that room, but I am still getting Apex warnings of >80°F temperature. I am going to remove the HoB and see what happens.

I would leave all the lights off and replace the lids, if any, with something that allows airflow. Put a fan blowing over it and it will help with evaporative cooling.

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You also have to consider where the heat goes.  My tidal35 puts probably 100% of the impeller heat into the tank.   My last hob had an the impeller motor on the outside so I'd be willing to bet a lot of that heat goes into the air and heats other stuff instead.

 

Same with an air pump.  The motor will warm up but depending on the air path it may not add hardly any heat to the air.

 

I don't have any hard numbers though, but if your shopping that'll hopefully give you some idea of what to look for.

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On 6/29/2021 at 9:12 AM, Streetwise said:

Unfortunately, one fish jumped from the bow. I put back the front part of the lid. My 20 is only down to 79F.

I realized that I forgot about another factor: I have kept a downstairs window open a bit for my cat, which was silly in this heat. I closed it, so hopefully I will see more of a drop.

its always the cats fault!🤪

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The tanks cooled down, and I let the window open again a bit for the cat, activated the lights, and got another temperature warning from the Apex. I set the AC back to 68°F, and closed the window again.

IMG_3084.JPG.724adfe1785d1094c76f34e2955cfe42.JPG

This is is an old building, with a dirt basement, a stone foundation, and terrible insulation. Fortunately, all the units are heated as one, so heat is included in my rent, and I have the only residential space in the building. I stock cooler species, so the heat is more stressful than the Vermont cold.

831535835_ScreenShot2021-06-30at19_30_19.png.382194967d055cf8d862011c509502e4.png

You can see where I opened the window and turned on lights for three tanks.

 

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On 6/28/2021 at 9:27 PM, Streetwise said:

My Apex can provide aggregate or per-outlet Amps, Watts, and Voltage. Let me know if a graph would be useful. I mostly just look at pH and Temperature. It is interesting to look at other data.

What kind of HOB is it? Is the motor completely molded into the body like an old biowheel, or does the motor hang off the bottom of the chassis like a Hagen? The primary source of the heat is likely going to be the magnetic coil of the motor that drive the impeller, and not from the impeller itself, so if it is 'Hagen-like' it might be enough to put a small fan blowing cool room air across the motor to help dissipate the heat.

It should be beneficial to see average current and watts of the motor on the HOB. With those numbers it might be possible to calculate the amount of heat generated, make an assumption that all of the heat is going into the water (instead of dissipated into the air) and use the volume of water to determine how much heat transfer there might be per hour. Because it is not a perfect closed system, the numbers would be approximate. I am an organic chemist, not a thermodynamicist, so I would have to dig the cobwebs out of my brain to do that math, but it should be possible.

 

Regards,

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On 6/30/2021 at 7:18 PM, Streetwise said:

@DShelton, this was the the HoB filter. The 16 and 20 each also have two ACO Nano Sponge Filters.

I changed too many things at once to make a hypothesis.

If you would like to see data, I have the data from probes and outlets on my 20 gallon.

I have looked at the pictures of that filter online, but I have not seen a clear picture of how the motor attaches. It looks like that the motor is molded into the body of filter, and possibly has water circulating around it. If that is the case then most of the heat would be transferred into the water.

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On 7/2/2021 at 11:09 AM, ArchwayAquatics said:

Your 5 gal bucket pic gave me an idea for an experiment. Monitor the temp in the bucket with the HOB on it. Get a baseline to start, then fire it up and watch what the temp does over the course of a day. Repeat over second day with a lid restricting airflow. 

If you have two thermometers you could track ambient and water temp for a better comparison.   You'll probably have to keep both in the same water for a few hours to make sure you can compensate for any temperature offset too.

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I have three cycled buckets with lights and sponge filters, one with decaying maple leaves, another with spare Mopani wood and mulm, and a third with invasive plants collected from Lake Champlain. I could move one of them upstairs next to my Apex and test. I think that I would need to put a rod across the bucket to hold the HoB.

To test, I would move the Apex Temperature probe and run for 24 hours, and then change filter or cover, and then run another 24. I would have to be disciplined with my AC settings, and the window for the cat!

I will think about it!

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Some creative use of command-strip-like hooks and fishing line might make sufficient support if you want to keep it entirely in the bucket. 

Another thought, since in my short time on this forum you appear to be a man of gadgets who might have one on hand, is to use a thermal sensor gun to see what the temp of the HOB housing is at the nearest point to the impeller coil. 

Also, have you checked the temp of the air at the termination of your air line?  I'm sorta curious what the difference from ambient there is. 

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