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  1. #1
    Senior Member nbreau's Avatar
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    Canopy Fan Placement

    My water is at 84F and it's suppose to go up to 31C today... I've got 2 fans and going to add 3 more.

    Should i direct the fans towards the surface of the water (45 degree angle?) or should they be pointed to go across the water as low as possible ?

    thanx....
    ======================
    sold the 77gallon back in 2005, looking to setup a nano

  2. #2
    Senior Member ALRHA's Avatar
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    i would direct those fans at the surface. i have the same problem today. i am not answering as a fact though, thats just what i would guess. if anyone knows otherwise, please let us know.
    Albert
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  3. #3
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    Personally I wouldn't go at the surface of the water. I would aim them up at the lights. Heat rises and you want to cool the air on top to cool down the tank. Blowing them at the water can cause major evaporation and quickly kill the fan.

  4. #4
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    Point the fans across the water. You want to increase evaporation. As the water evaporates, it lowers the water temperature. You also want all the fans pointing in. If you use a fan to draw air out of the canopy, because of the moisture, the fans don't seem to last as long. You can also put fans on your sump to help lower the temp. Just remember to top up the evaporated water.

    If things get out of hand, get a few of the freezer packs from Canadian Tire. Once frozen, drop it in your sump to help lower the water temp. Rotate - one in sump and one in freezer. I don't think you will have a problem with 77 gallons but with a smaller tank, watch that you don't lower the temperature too far, too fast.

  5. #5
    Senior Member ALRHA's Avatar
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    PowderBlue, why would it kill the fan, he is blowing AT the water, not from the water so it is drawing air from the room, that should not be a problem, unless you are worried about splashing in which case nbreau will have to make sure to place them in a "splash-free" area. Cooling the lights may help keep the water from getting hotter, but to cool the water, the best thing to do would be to cause as much evaporation as possible. First of all, you get to top off with cooler water which will help cool the tank, and secondly, it is the evaporation process itself which cools the water (same thing with humans sweating).

    Now for the lesson:
    For H2O to convert from a liquid to a gas, energy is required (endotrophic reaction). This is just like boiling a pot of water and making steam. the heat from the fire is used to convert the water into vapor. In your tank (or on your skin) when the water evaporates it is going into gas form and will use the heat as a source of energy from its surrounding (your tank or your skin). As a result the surrounding water now contains less heat and is cooler.
    the rate of evaporation will be affected by temperature (the warmer the water, the closer it is to vaporizing) and by the humidity level (which is how much water is already in the air) the higher the humidity, the close the air is to being saturated with water and the less room for more water or more evaporation. Blowing the fan at the surface will provide fresh dry air to help in the evaporation as opposed to the air directly above the tank which already is humid from the last evaporation. moving air also helps raise the evaporation rate as moving air is at a lower pressure (that how an airplane can fly, the air moves faster above the wing than below it causing low pressure on the of the wing which causes an upward force called "lift") the lower pressure above the water means there is less air pushing down against the surface and makes it easier for the water to evaporate. for a quick experiement on how moving air can speed up the evaporation process, take a shower (please) and stand in front of a fan when you come out. see if you dry faster than if you didnt. also note how you suddenly got so cold by all the fast evaporation. your tank will feel the same way.
    the question is which way would cause more evaporation, pointing the fan AT the water or ABOVE the water. i would say if you have only one fan, the blow it at 20 degrees so that it can cover more area on the water surface, if you have more fans, just tilt them enough so that you can cover the entire surface of the tank.

    answers your question?
    Albert
    My Photos

  6. #6
    Moderator Krugar's Avatar
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    Related but slightly off topic, I'm building a custom wooden canopy for my nano & I was going to put 2 small fans in it:

    1 pulling fresh air in under the canopy & 1 pushing the air back out. My thinking was this would help increase the gas exchange and keep the tank cooler by increasing the air flow.

    Does anyone see a problem with that?

    Cheers!
    There is nothing so permanent as a temporary measure.

  7. #7
    Senior Member ALRHA's Avatar
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    i would just blow the cool air from the room into tha hot canopy (i am doing the same thing in mine). you dont need to blow the air out, it will find its own way out. also as mentioned above, the moist air in the canopy may ruin your fan with time.
    Albert
    My Photos

  8. #8
    Senior Member ABahn's Avatar
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    I would think they are more easily installed parallel to the water surface. You simply want to vent the heat. It would be better to blow into the canopy. You can connect them up to a household thermostat and relay to dial it in to your liking. Set and forget......

  9. #9
    Senior Member Flame*Angel's Avatar
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    Definitely fans on the water and get as much evap going as you can - replace with cooled top off water. If you have a sump get fans on that too, the biggest ones you have.

    Dang I'm glad I have air conditioning today! It's 37C in the shade on my back deck. My tank still got up to 82F though.
    Susan

  10. #10
    Senior Member
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    yesterday i installed one 9" clip on type($11) temp before 84 now temp 81.not bad for $11.i installed it at the corner of the canopy and blowing accros the water.

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