Temperature Control....gotta loose some heat
 

Well, the new tank is up and running and the 400W hallides look awesome...the only down side as I expected is the heat.

I will be adding a couple of 12V fans blowing directly down on to the water but I am looking for any other ideas to keep the temp down.

Joel

Temp control
 

1. Could raise the lights a bit higher.
2. A couple fans blowing across the top of the tank instead of straight down.
3. Air conditioner for the room.
4. Chiller.

I installed a couple of radioshack fans in my light hood and they work like a charm. During the summer months when it gets really hot I also have a 1/4hp chiller that gets the job done.

Well it looks like Fans are a viable solution.

I put a 120v small house fan blowing in from the back corner (it is a corner tank) and I lifted the lid with some blocks 1/2" to allow the hot air to be forced out. I ran my hallides for about 5 hrs last night and the temp only went up 1 deg.....now only if this will hold true over the summer.

re temperature
 

do u have a lid on your tank?
If so, I would think that is the major cause of your heating problem. I think that the lid would act like a magnifying glass under the MHs...
I dunno..but just my opinion.

with 400 watt lights you are probably going to have to invest in a chiller.

Hoping not to have to go the chiller route....the fan seemed to do the trick now all I have to do is wait till summer.

I have dual 400W halides, and have an enclose canopy. I also have glass covering my tank. Two 12V fans running while the lights are on prevent them from raising the tank's temp even a degree. I would consider trying this if you can. I think the enclose canopy and only fan openings allows more efficient air circulation for providing fresh/cool air and getting the heat out.

Chris

Edit: I also have no sump, I have a 100gph flow 23g refugium above the tank(sitting directly over the lights too) that needs to be heated during the day sometimes to maintain a proper temperature.

Definately install some fans right into your hood. You can do a few configurations, like one blowing in, on blowing out, or 1 or two blowing across to a vent in the other side.

Heat from the lights is going to heat the surrounding air, but not the water so much directly. Blowing fans at the lights will distribute this heat into the airspace surrounding the tank, but I don't think it will be too effective at actually cooling the tank. Eventually, if all the air surrounding the tank/sump gets beyond the tank temperature, it will start to heat the tank, though.

...unless you've got a really closed-in light canopy that traps a bunch of hot air directly above the tank, then this effect could be greater.

I think the bigger effect is the energy of the light hitting the rocks heats up the rocks which then heats the water. If fans on the water surface won't do it you are going to be really pressed to avoid some sort of water chilling.