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Water Temperature Control in an Aquarium

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df0807

New Member
I have a salt water aquarium where the water temperature can get too warm.

I've installed a CPU cooling fan on the hood and find it is very effective in bringing down the temperature. I'd like to put this on a thermostat.

I’ve disassembled a working aquarium heater and plan on wiring it to the fan. Here is the problem: The heater logic is opposite of what I need.

When the water is too cold, the heater comes on. When the water is warmed to the setting, it turns off.

This sounds like a job for a RELAY… one that is open when current is applied and closed when current is removed. Also, it needs to be an AC relay.

I’ve been looking on line and have found dozens.

I’d be interested in hearing suggestions on the relays for this application.

Thank you in advance.

Nick
 

MikeMl

Well-Known Member
Most Helpful Member
I have a salt water aquarium where the water temperature can get too warm.

I've installed a CPU cooling fan on the hood and find it is very effective in bringing down the temperature. ...
Nick, I question this. If the water in the aquarium gets too warm, probably because the ambient air temperature is warmer than the water in the aquarium, how does blowing warm air onto cooler water cool the water?
 

bychon

New Member
The water in the aquarium will move towards the dew point temperature of the air, not the sensible temperature of the air.
 

3v0

Coop Build Coordinator
Forum Supporter
Nick, I question this. If the water in the aquarium gets too warm, probably because the ambient air temperature is warmer than the water in the aquarium, how does blowing warm air onto cooler water cool the water?
Increasing the airflow over the water will increase the rate at which the water evaporates. The process of evaporating the water absorbs heat from the water that remains in the tank.
 

MrDEB

Well-Known Member
I would think a DIY radiator and cpu cooling fan would cool better than blowing air across the top of the water.
Being salt water copper and aluminium are out. Use a coil of 1/4" plastic tubing or two then blow air across then like a car radiator.
Using this method would maybe prevent a thermocline within the tank (cool water on top warm on bottom)
Just use the present aquarium pump, insert the "radiators" and add cooling fans. Use a thermostat in the tank, not on the cooling system.
 

Boncuk

New Member
How about using cold mist?

The mist will distrubute over the entire water surface allowing to cool the aquarium water (with the filter pump running).

Here are some screenshots.

This mister is made of stainless steel and can be dunked into the aquarium.

Boncuk
 

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Lighty

New Member
I would think a DIY radiator and cpu cooling fan would cool better than blowing air across the top of the water.
Being salt water copper and aluminium are out. Use a coil of 1/4" plastic tubing or two then blow air across then like a car radiator.
Using this method would maybe prevent a thermocline within the tank (cool water on top warm on bottom)
Just use the present aquarium pump, insert the "radiators" and add cooling fans. Use a thermostat in the tank, not on the cooling system.
A cooling system where the water just runs though a thin pipes (like above) wouldn't work, its designed to cool something much hotter than ambient temp down to ambient temp, where a evaporator can cool way below the ambient temp, it uses the evaporation process to cool the water, like sweat does to a human.
 

Boncuk

New Member
Blowing air over the water surface for cooling is not uncommon with aquariums. The OP only wanted a way to regulate it.. not a different cooling solution.
That sounds OK as long as the ambient air is cooler than the aquarium water.

Obviously the aquarium water gets heated by the ambient air. That little bit of evaporative cooling by blowing air over the surface might not suffice reducing water temperature.

Cold mist reduces water surface temperature considerably and with the water being circled by the (most necessary) circulation pump it will attain the desired temperature.

Boncuk
 

crutschow

Well-Known Member
Most Helpful Member
Obviously the aquarium water gets heated by the ambient air. That little bit of evaporative cooling by blowing air over the surface might not suffice reducing water temperature.

Cold mist reduces water surface temperature considerably and with the water being circled by the (most necessary) circulation pump it will attain the desired temperature.
He has already stated that the fan blowing over the water is very effective in reducing the temperature. Why make the task more complicated?
 

df0807

New Member
Nick, I question this. If the water in the aquarium gets too warm, probably because the ambient air temperature is warmer than the water in the aquarium, how does blowing warm air onto cooler water cool the water?
Fact is, when the fan is off, the tank temp is around 86.5. When I keep the fan on, I can drop it down to 81.5
 
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Mikebits

Well-Known Member
What sort of fish do you have? Are you sure water temp is too high for these fish? What is the water temp that you consider too high? Just curious.
--------------edit------------------------------
I just re read and see the water temp is 86.5F. Why so high? Do you have high wattage lamps on the tank?
 
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Lighty

New Member
Obviously the aquarium water gets heated by the ambient air. That little bit of evaporative cooling by blowing air over the surface might not suffice reducing water temperature.
It would still cool the water even if the ambient air temp is higher. If I can remember from my school days, evapouration is an Exothermic reaction.

I have about a 800L system, and a fan can drop the water temp by a good 2-4 deg C.

But yes, crutschow said, its a whole new topic.
 

Boncuk

New Member
It would still cool the water even if the ambient air temp is higher. If I can remember from my school days, evapouration is an Exothermic reaction.

I have about a 800L system, and a fan can drop the water temp by a good 2-4 deg C.

But yes, crutschow said, its a whole new topic.
Agreed.

The question is that: Will evaporative simple cooling suffice to reduce temperature to the desired value.

I use an evaporative cooler in my living room next to my chair consuming approximately 20l of water within 12 hours.

The air hitting my body is about 4 deg C below ambient temperature, which doesn't satisfy at all. (ambient temperature 46 deg C and fan outlet 42 deg C - still much too hot, wasting 80W of electric power + carrying water regularly to feed the machine). This device won't even change room temperature by 1/10 of a degree.

If the aquarium water surface is large compared with the surface of the basin that method might be reosonably efficient.

May be Crutschow is right saying it's a new topic, but I have experienced that very often the OP is directed to another approach to solve his problem.

Just some numbers using a cold mister rated 24VAC/1200mA. Initial temperature 32.7 deg C. With cold mist activated the water surface temperature dropped to 27 deg C within one minute (bowl content approximately 1 1/2l). To create a temperature drop of 5.7 deg C (by evaporative cooling) you need a fan causing waves on the aquarium water surface and I doubt a fancy CPU fan will be able to do that.

CPU fans are axial fans with low pressure and high volume. To create waves you need a radial type fan with high pressure at lower volume.

I certainly do not intend to talk anybody into anything, but these are the facts.

I go along with our Kaiser Wilhelm II who said: "Jeder soll nach seiner Facon glücklich werden." (Everybody should become happy his way.)

Cheers

Boncuk
 
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