[inuyasha_lover_21]

I am going to buy the tank bred ones in a few weeks. How well can they handle the temp fluctuations? My metal halide heats up the water to 82F and at night it will drop to 78.6F.

[leebca]

This is an undesirable swing in temperature.

When temperature drops, the fish will lose some of its protective coating making the fish more susceptible to infections, diseases, and problems.

If you have properly quarantined and treated the fish and the display tank/system it is going into is disease-free, the temperature swing will probably be okay so long as it isn't any larger.

There are ways to reduce the halide effect. Use a fan to blow across the surface of the tank; circulate the air in the room; use a fan at the halide bulb to remove the heat from hitting the aquarium; plus more.

[inuyasha_lover_21]

I will bring in my old tower fan And have it lifted up. It has 3 fans on it. I will have that blowing on top of it. Thank you for the suggestion.

[rjs5134]

I have the same problem, almost exactly. The MH's raise the temp by almost 5 degrees. I've removed the glass canopy(needed to keep blue dot jawfish and firefish from jumping), raised the light from 6" above tank to 9" and still have the same problem. I did increase the photoperiod for the MH's at RL's recomendations. But this wasn't enough to solve the problem.

I have a chiller rated for a 180 gallon tank which will be hooked up shortly, but it recomends setting it for a 4 degree variance. I can set it as low as 2 degrees. Obviously 2 would be better, but is that enough of a tolerance? I suspect it will be more of a concern for the corals and have posted soem questions over there.

[Reefland]

I think you can consider the temperature swing ok if you can keep it to 2-3 degrees during the day.