Kessil

Do I need a fan?

M

maxs55

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Hi All!

I'm approaching my first summer with the tank, and I am wondering if I need a fan for my tank. Do reefers in california generally have fans or chillers? I keep my AC set to a maximum of 78, generally closer to 72, but on days where it is hot, I have noticed that the lights heat the tank into the low 80's.

I currently have a Reefer 525(110 gallon tank, 30 gallon sump) that has a 5' x 2' netted top.

Thanks in advance
Max
 
You can try fan first, if that doesn’t work well, then budget for a chiller. It’s a $30 or $300 decision.


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You want a rimless clip on or a regular fan that you can put on somewhere to blow the air on surface?


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You set your AC at 72 and the tank gets up to 80? That doesn't seem possible.

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I would definitely install a fan now. When you need it, it’ll be too late.

I’d recommend a clip-on desktop fan personally, they are quieter and blow more air vs the multiple computer fan setups. There are lots of options, none of which is obviously the best. Depends how you will be mounting it, and how you’ll be powering it.

For reference this is what I’m using currently but I’m powering it through a DC jack on Apex:

Amazon.com: Alagoo 12V 6''Car Cooling Fan Automobile Vehicle Clip Fan Powerful Quiet Ventilation Electric Car Fans with Adjustable Clip & Cigarette Lighter Plug for Car/Vehicle: Car Electronics

Amazon.com: Alagoo 12V 6''Car Cooling Fan Automobile Vehicle Clip Fan Powerful Quiet Ventilation Electric Car Fans with Adjustable Clip & Cigarette Lighter Plug for Car/Vehicle: Car Electronics
www.amazon.com

I have set on medium speed and it’s more than enough to keep my tank (RSR750) with lights and everything on at 78 even if the house gets up to 80.
 
JVU said:
I would definitely install a fan now. When you need it, it’ll be too late.

I’d recommend a clip-on desktop fan personally, they are quieter and blow more air vs the multiple computer fan setups. There are lots of options, none of which is obviously the best. Depends how you will be mounting it, and how you’ll be powering it.

For reference this is what I’m using currently but I’m powering it through a DC jack on Apex:

Amazon.com: Alagoo 12V 6''Car Cooling Fan Automobile Vehicle Clip Fan Powerful Quiet Ventilation Electric Car Fans with Adjustable Clip & Cigarette Lighter Plug for Car/Vehicle: Car Electronics

Amazon.com: Alagoo 12V 6''Car Cooling Fan Automobile Vehicle Clip Fan Powerful Quiet Ventilation Electric Car Fans with Adjustable Clip & Cigarette Lighter Plug for Car/Vehicle: Car Electronics
www.amazon.com

I have set on medium speed and it’s more than enough to keep my tank (RSR750) with lights and everything on at 78 even if the house gets up to 80.
Click to expand...
THanks! I'll look into this.
 
FYI: Evaporating a gallon of water is 8,700 BTUs.
So a VERY effective way to cool the tank.
Key: Surface agitation, have a good ATO, and be careful of humidity problems as that water evaporates.
What is not so critical is the fan size.
 
rygh said:
What is not so critical is the fan size.
Click to expand...
I disagree, wind speed over the surface is MUCH more important for evaporative cooling than surface agitation. Not even close. The idea is that you are replacing the steady-state water vapor saturated air adjacent to the surface of the water with new air that is not vapor saturated. Once the tiny layer of air over the surface of the water is saturated, it stops evaporating (and cooling). Continuously replacing the humid air with dry air keeps the evaporation (and cooling) going.

Evaporative cooling is why we sweat when we are hot. Consider the difference between being hot and sweating with minimal air movement vs a strong breeze or fan. No comparison which cools you faster.
 
JVU said:
I disagree, wind speed over the surface is MUCH more important for evaporative cooling than surface agitation. Not even close. The idea is that you are replacing the steady-state water vapor saturated air adjacent to the surface of the water with new air that is not vapor saturated. Once the tiny layer of air over the surface of the water is saturated, it stops evaporating (and cooling). Continuously replacing the humid air with dry air keeps the evaporation (and cooling) going.

Evaporative cooling is why we sweat when we are hot. Consider the difference between being hot and sweating with minimal air movement vs a strong breeze or fan. No comparison which cools you faster.
Click to expand...

Agree with the physics concept, but need to do the math.

My large 240G tank is about 8'x2' of surface area.
Let's assume fan blows across the water, roughly a 6" stream of air.
(My canopy is about that size, but I think given flow, that seams reasonable even with no canopy)
That is 8*2*.5 = 8 cu ft.
A simple cheap 120mm computer fan is about 50 CFM, usually more.
Which means that the air above the surface is completely replaced (60/50*8) = 9.6 seconds.

So I just don't see air getting super saturated in 10 seconds.

Velocity of the air certainly impacts evaporation though, I am not denying that.
But if memory serves, it is not linear, it is some exponential less than 1.
 
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