Bridging the 3.5 degree thermal gap...

[JeremyAN7]

Hey folks.. So now I have this nifty-neatoh (technical term) MH fixture.. 2x15hqi+2x110vho. It's great, but as you may expect, is raising the tank temp at day time quite a bit. I don't currently have a chiller.. BUT, I'm now getting a 3.5 degree day/night swing (likely summer only as the ambient temp in the room is 8 degrees warmer in the summer, and in the winter, I'd imagine the heater will just work less..)

The MH balast is under the tank in the stand, which produces a reasonably large amount of heat. My plan is to put an exhaust fan there to move the heat out from under the stand. I figure that's good for maybe 1 degree of swing.

I plan on putting a small PC fan in the hood (outside the fixture to move some air up there and keep the air just above the water cooler.. I figure that might be good for about 1 degree, as it may pick up some evaporative cooling too. (this will be on the same timer as the MH about 7 hours a day)

I also plan on installing the ICEPROBE (mini chillier) which in a 72g tank is like spitting in the wind, but I figure it's good for about 1 degree...(this will be on the same timer as the actinics for 10 hours a day)

Which when you add them all up, may be good for about 3 degrees.

Doing all this, do you think I'll get my day/night spread down to 1 degree or less? (that's the goal)

 

[MikeG]

Fans will help tremendously to cool the tank. I don't think that you need to change a 3 degree swing though. My tank swings 4 degrees every day with the light cycle and I haven't seen a problem.

 

[JeremyAN7]

I guess I'm just going for the low hanging fruit (with the exception of the IceProbe) to minimize it.

 

[maurod]

A 3 degree swing is nothing. 5-7 degrees, you can have a big problem. Fans alone should give you the slightly cooler temp you desire.
Good luck.
M.

 

[OceanGuy]

A small fan from above blowing directly on the water will lower the tank a few degrees. You can hook it in with your light timer so they go on at the same time.
Small swings are natural on the reef. There is a big difference between the night and early morning and the mid day temperatures of the air and water.
Good luck in gettng it the way that you want it.

 

[Scuba_Dave]

My tank ranges from 78 to 84 on a regular basis
And stuff grows like weeds

 

[Ray]

Go to wallmart and buy a couple of desk fans, one to put on the sump and one across the top of your tank. This is what I do and I have never run a chiller and usually stay between 79-81.5

 

[maurod]

My tank ranges from 78 to 84 on a regular basis
And stuff grows like weeds

Your tank does not get stressed as you approach 84 ?
I know mine was in very bad shape at 85, only one coral died but lots of stuff lost color.

M.

 

[Scuba_Dave]

Running 2.5 years same way, high of 85/6 on one occasion, low of 75
My purple rim cap is huge, growing out of the water
My Orange cap I had to chop the bottom 3" off & lower it into the water

In the summer my tank runs around 83/4 at a peak for the most part, cooling off at night to 78-80

In October I had to do a clean up & get rid of a bunch of stuff
Most of it I just gave away

I'll be doing the same thing again shortly