keeping water cool?

[69camaro540]

i have a 120g reef ready tank. i built a canopy for it and currently have 2 400 watt metal halides. i know i need to add some fans to cool the canopy, but should i add 2 or 4. i am trying to keep things cool without having to buy a chller. the setup is new so there is nothing in the tank. i am planning to have sps corals and some clams and a few fish. any suggestions on trying to keep the water a little cooler? the tank temp is 76 degrees without the halides on. after 6 hours the temp goes to 82 degrees. any suggestions? thanks jody

 

[PatMayo]

I doubt you are going to be able to do it without a chiller. Do you have a glass top on it?

You can try, I would do 4 fans. I don't think you can put too many in there.

Regards,

Pat

 

[69camaro540]

tank does not have a glass top. the halides are 10 inches above the water. the canopy is about 14" tall.

 

[AZDesertRat]

Its going to be tough without a chiller but it is possible. I ran my 100 G with 2x250 MH and 2x140 VHO for about 18 months without a chiller. I have 2 4" fans in the canopy, one on either end blowing in and 4, 4" holes in the top directly over the reflectors so light doesn't hit the ceiling but heat escapes. I also used a 6" clip on fan over the sump.
The problem with using fans is your evaporation is tremendous, I was replacing 6 gallons every other day. Now with a chiller, the canopy fans are slowed way down so they are silent and the sump fan is only a backup if the chiller were to fail. My evaporation is now only 5 gallons every fourth day so it less than half what it was.
76 is a little cool for most things. I try to keep my tank at 80 all the time with only a 1 or 2 degree swing in 24 hours.

 

[waldomas]

Put a couple of fans on the same cycle as youre halides.

 

[waldomas]

I have a built in 180 gal with 3 250w pendants 10 inches from water surface ( no canopy). I have 1 12 inch fan on my sump (no chiller). My temp does not go above 80 deg. If that doesnt work add another fan! I do top off 35 gal/wk.

 

[Sindjin]

I put 2 fans into my canopy pulling air IN. In addition I have a 7" clip on fan blowing across my sump.
My tank temp stays at 77 to 79 now.

In addition, I do have a top-off system to aid with evaporation.

 

[Ti]

Use Clip on fans and top off.

 

[69camaro540]

are you guys using standard 4" fans in the canopy or are you using icecap variable speed 4" fans. is there any advatage over the variable speed?

 

[supertech3]

the advantage to some of the variable speed fans are being quieter depending on the manufacture. some of the variables will also have temperature sensing to provide more airflow when temp rises

 

[AZDesertRat]

Just buy good quality constant speed fans like Vantec Stealth or others and use small variable voltage power supplies to control them. Variable DC Power supplies are available at Wal Mart, Harbor Freight Tools and Radio Shack for less than $5 in most cases.

 

[69camaro540]

when using the fans, is it better to be blowing into or blowing out of the canopy? thanks

 

[AZDesertRat]

Blowing in. Blowing out carries salt spray and the fans don't last near as long. Some try one in and one out but when you think about it, you only have the CFM volume of one fan so only get 1/2 as much cooling. You could put 10 fans in a row but it will only blow as much as 1.