How do you position your fan

[mab]

Hi guys,

I'm just wondering what is the best way of positioning the fan to cool down the water temperature lowest possible.

I've seen in this forum, two positions

1. fan facing down (to the gravel)
2. fan 45 degress across the water level
3. others? Please explain by replying this thread

Please also join in the poll to see which is the most favourite fan position.

Thanking you in advance for all the valuable feeback.

Cheers
mab

[celticfish]

lemme see if i remember my fluid dynamics correctly...

ideal flow over the water should be in the direction of the longer side and, parallel to surface and as close to it as possible. the flow should blow less humid air over the surface to absorb more moisture then flow away from the tank. the flow should be gentle but most fans are too strong in my opinion.

mind you, this may not give you the most cooling but if you can match the work done by the fan to the cooling effect it will give you the most efficient method.

so in practice, having the fan point into the water at a gentle angle (15 to 20 degrees with aiming point at the centre of the length) would be best.

celticfish

[Justikanz]

I think the point is to use the fan to evaporate the water and the evaporated water needs to be blown away from the water surface. Thus, I personally think it is less efficient if the fan is ponting down towards the gravel. My 2 cents...

[|squee|]

Mine is 45 degrees. I agree with the fluid dynamics thingy. It's the evaporating water surface that cools the tank, so we want maximum area of water that the "wind" from the fan hits.

[mab]

Originally, my fan was 45 degrees. Coolest I got was 27.5. Then last week I started to have a thin layer of protein on the surface . Water temperature has since been above 28.5 degrees.

Last night, I change the fan to point downwards & tonight got back 27.5 degrees. I intend to buy another fan & see if the temperature can go lower.

Cheers

[celticfish]

hi mab,

one more point to add. there are two points to consider, airflow over the water and surface agitation. both will contribute to evaporation and, therefore, cooling.

although i haven't really used a fan myself, i reckon you will get better cooling if you can create an airflow over the whole surface. for example, four small fans over a wider area will cool better than two fans covering a narrower width.

celticfish

Originally, my fan was 45 degrees. Coolest I got was 27.5. Then last week I started to have a thin layer of protein on the surface . Water temperature has since been above 28.5 degrees.

Last night, I change the fan to point downwards & tonight got back 27.5 degrees. I intend to buy another fan & see if the temperature can go lower.

Cheers

[cherabin]

Although i voted for 45 degrees, my 2' actually has its fan resting on the egg crate tank cover. Still doing a pretty decent job at maintaining 26-27 degress celcius.

[AkionLCG]

Mine is placed 45 degrees at the longitudinal end.

[anttz]

Most people said 45 degrees. But funny thing is I recorded lower temperature by placing the fan face down.

In theory, I agree with squee on blowing on maximum area of the water surface. But in practise somehow the result is otherwise??????

I also noticed that NA has all the fans facing down.

[bettarism]

Most people said 45 degrees. But funny thing is I recorded lower temperature by placing the fan face down.

In theory, I agree with squee on blowing on maximum area of the water surface. But in practise somehow the result is otherwise??????

I also noticed that NA has all the fans facing down.

yeah. i noticed that also..But i think NA fans are all slow and soft blowing fan. The water disturbance are very little compare to using PC fans.
If we use a strong fan, it will caused alot of water disturbance which in turn caused Co2 loss.

[freezze]

how u define strong or weak fan?

[bettarism]

how u define strong or weak fan?

I suppose it should be the rotary speed.
Most aquarium Fan are design with lower rotary speed.

[freezze]

the fan we used usually do not show the rotary spd... only voltage n amps..

[grey_fox]

probably visually...

[Aeon]

Mine is more like 10 - 15 degrees. Day temp is 26 - 27 degC.

[vincentlii]

The fan is for what ?

[tcy81]

i position my fan at a angle less than 45 degree.

[Jaffar]

Mine is placed at a angle so that the water ripple is not to strong. Definitely not facing down.

[doubleace]

Mine placed at 90 degree angle and i wonder wanna add another fan for my 4ft tank (currently using 1 fan) and temp is at 27-28 degree as for my 2ft i use only 1 fan with the same angle and the temp is at 26-27 degree.

[Ben Lim]

My preference is 45 degree for a wider coverage. Of course wind force is not as intense as compared to 90 degress but then the fan is "on" round the clock to make up for the intensity.