Fans causing turbulence resulting in moving shadows

[Golfmad]

Hi

I experimented with different angles for my fan and found that cooling worked best for my tank at approximately 55-60 degrees. However, it is also at this angle that the turbulence is greated. This turbulence has also resulted in moving shadows being cast onto the tank. Does anybody know how to eliminate the moving shadows besides turning off the fans ?

Tks for help.

Rgds,Kelvin

[DEA]

it's the turbulence that exposes more water to the air, which explains why the fans are most effective at that angle

i suggest you change the angle of the fans
anyway, i have the same thing, and i like the moving shadows

[David]

think like what yimin has mentioned, as this is the effective angle for greatest surface agitation.......

I think the shadow effect is pretty.....in fact in my living room, the shadow effect is casted all over the room and I like it......

[sherchoo]

Yes, some people like the shadow effect while some find it very distrating. Now, my question is, what light are you using and how much? To reduce this effect, you would like to change the angle of the fan (as mention ealier) but that would also mean reducing the cooling power. The key is balance.... try to reduce the surface agitation to avoid shadows while not elimating too much cooling power.

Good Luck!

[Golfmad]

Hi Guys

Tks for all the comments. I guess I have gotten a little used to the shadows after 5 days of looking at it. I am using 3x150w MH lights mounted 1 ft above the water. I was thinking of rigging up 2 sets of fans. 1 set will be set up for optium cooling during "lights off" hours and another for MH cooling during "lights on" hours. Not sure how well this will work but will give it a try.

Rgds,Kelvin

[vinz]

How about:
- 2 sets to cool the tank water. One set 24 hrs and one set following light timings. You'll need less cooling after the lights are out.
- another set to cool/ventilate the MH.

[Golfmad]

Vinz,

even though I need more cooling when the lights are on, I have to turn off the turbulence causing fans as they are the ones responsible for the shadows. BTW, what temperatures are you getting with your 3 fans with and without lights ?

Tks,Kelvin

[vinz]

My fan timings are the same as the lights. In the current weather, my thermometer shows 28 to 28.5 degrees celcius. During the rainy season a few months ago, 26.5 to 27 and occassional 26. 1 to 2 degrees difference seems to make quite a difference to the tank.

I added a 4th fan recently (I bought 4 but used only 3). The speed and air-flow of the first 3 fans seem to have reduced significantly... not sure if it has an effect on the temp.

I'm considering getting a chiller for my 6 ft tank. I would suggest that you do too, especially since the tank is deep (surface to volume ratio is low) and you're using MH lights. Cool temps seem to make quite a diff to some plants.

[leafhorn]

The shadow effects like currents of the river, very nice!

[Golfmad]

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On 4/28/2003 3:03:50 PM

My fan timings are the same as the lights. In the current weather, my thermometer shows 28 to 28.5 degrees celcius. During the rainy season a few months ago, 26.5 to 27 and occassional 26. 1 to 2 degrees difference seems to make quite a difference to the tank.

I added a 4th fan recently (I bought 4 but used only 3). The speed and air-flow of the first 3 fans seem to have reduced significantly... not sure if it has an effect on the temp.

I'm considering getting a chiller for my 6 ft tank. I would suggest that you do too, especially since the tank is deep (surface to volume ratio is low) and you're using MH lights. Cool temps seem to make quite a diff to some plants.
----------------

Was thinking very seriously of getting the chiller but am facing a problem with the hot air from the unit. My tank sits within a wall cupboard so the hot air would be a problem unless I leave the door open the whole time which is not a feasible option. Mounting the chiller remotely was also considered but was told that this is not prefered. Anyway, I would going to exhaust all my fan options before looking at putting in the chiller. Pls let me know when you put yours in and are you going to leave the chiller sitting in your living ?

Rgds,Kelvin

[David]

Hi Golfmad

I seriously doubt if 2 fans is enough to cool the tank to a decent 27 to 28C. I have 2x150watts MH with 2 AC Fan and still stuck at 29C. considering that I am on the 12th floor and very airy. The warm months are coming again......

Getting a chiller is one good consideration. Do you have air-con in your living room? If yes consider turning it on with 1 AC fan....then both your family and your tank will be happy....you may consume alittle more electricity....though.

[vinz]

Kelvin, yes it's going to be in the living room, no choice. Most likely under the side table which I hope is tall enough.

I've considered remote before. It's possible. The 2 main problems will be temperature rise due to long exposed piping and reduced (which is not a bad thing for the chiller, but may effect your filtration) flow from long piping. Solution: mount the pipes in aircon trunking and/or wrap with insulating materials. Flow can be settled with a dedicated pump. Since you have 2 filters, you may not need a dedicated pump.

Are you able to get the carpenter to modify the cabinet a bit? Possible to cut holes in the sides and mount fans to vent your chiller compartment? Or install louvres... especially where the chillers main vent/fan is situated.

[Golfmad]

Hi David

Actually, with 2 fans going now, I can get the temp to 27.4 c w/o lights and to 28.6 w/ lights. This is with the doors open. The room is airconditioned but it may not have much impact as the cool air may not get into the cupboard where the tank is sitting.

Hi Vinz

Drilling holes in the cupboard is out of the question as this is a new cupboard(done at the same time as the tank). I have however, a chamber at one end of the cupboard which leads to the attic. Since hot air rises, I am hoping that the hot air would be forced up this chamber.

Anyway, what I want to do is try different numbers of fans and angles to get the best cooling possible. I will then start monitoring with the doors closed. If temp is still too high, I will chiller or more to warm temp plants.

Rgds,Kelvin