Installing Fan

[nakazoru]

I'm going to install 2 fan in my hood to cool the tank. My tank has a enclosed hood. Bros out here, do you suggest the fan to blow into the tank or outward to acheive best cooling.

[zeotz]

IMHO, need to blow into the tank. The air has to blow directly over the water surface to promote evaporation(about 1~2 litres per day in my 4ft tank case) which in turn cools the water in the tank.

Best that the fan should draw air from outside the hood and not within the hood. Avoid placing the fan over the lights cuz then you may be blowing hot air into the tank. But even then, it is not very signifcant in heat transfer into water in main tank cuz the warm air blowing on the water will still give rise to evaporation which is the main mechanism if you are cooling by fan method

[nakazoru]

But was it not a fact that hot air rises thus blowing it out on the top removes the hot air. By introducing vent in the hood enhances air circulation. I was thinking of blowing in also, but most air cool mechanical design (not fish tank) has incoming cooling air at the side or bottom and outgoing hot air on the top. But fish tank, we can't have that design since fan is confined to the top.

[Kelmen]

since you go for 2 fans, more nicer.

1 in , 1 out. That's the point of "heat" exchange.

Just in no out, not efficient. Will be very bad if outside air is far more hotter. Not surprise during hot season.

1 in at 1 end, the other out at another end. Best if can place the in at an angle toward the water surface, as to blow across the water surface, not direct hit them.

HTH

[zeotz]

agree... fan should blow across water surface . .. and that more ventillation the better ... but IME, the latter is not critical cuz the principle is cooling of water by evaporation, not by ventilation or conduction or convection. so the hot air/cool air thing is not that important.

In my case previously, I had a closed up hood. and blew into the hood, across the water surface from an opening on one side (basically the hood flap). the blown air was warm due to blowing across lighttube on the way but still water temp managed to drop by 2 deg (compared to not using fan). i'm using a chiller (set at 29deg) now cuz too lazy to top off water everyday.

[haroldteo]

previously , i have installed 4 small fans bundled into one and another larger fan. After some time, the fan became rusty and dirty with dust and salt deposit.

I also experinced electric shock when accidently I touch the casing.

My advice is to get a chiller but the only negative part is the electicity bill.

[nakazoru]

2 deg is great. Evaporation is really that great. My tank is always at 29 -30 deg. Must really get down to installing it. I think I understand it to blow at the water now.

Thank you guys.

[nakazoru]

Yea, I understood that electrical shock is a concern. My tank does not have air bubble splashing so I guess it is all right, but salt do get crystalize so how outside the tank. My intent is to use 24V fan instead of 230V, and adding 24V 0.05 A fuse to the installation, so I dun worry about the short circuit.

As for the dust, I guss that will go into my maintenance schedule. hahaha .

I love to have a chiller but my tank have no cabinet for sump, chiller or even the canister filter I have now. These make my living room ugly you know. Every thing sits outside. My wife complains that the equipment is a eye sore in the living room... especially after spenting ID to reno the house.

Even now, electrical bill average at 250SGD monthly , I can't imagine adding a chiller..... Crazy oil prices, it is a monopoly, dame the OPEC