temperature swings

[Delphinus]

I'm never home during the day, so I've never noticed this.

I run my 75g tank at 26 degC (about 78F for you non-metric folk :D ). When the VHO's turn on, so does a simple clip-on fan aimed at the water surface.

Without this fan, when the 2x250W turn on, the temperature jumps to 30C (about 86F). So the fan is a bit of a necessity.

But, I just discovered, since the VHO and fan turn on about 1.5 hours before the halides, my temperature DROPS to 24.5C (about 76F). When the halides are on, the temperature comes back to 26C by about 12 noon (so it takes about 1.5 hours to go from 24.5C to 26C), this is why I never noticed there was a "daily temperature dip."

Is it enough of a dip to change things? Or could I leave it like this?

I could run the fan on the halide timer instead of the VHO timer, but I always liked the fact that the fan would stay on after the halides turned off a bit. Besides I want the fan to prevent the VHO tubes from getting too warm.

To be fair, it is a bit of a cold day today, it's probably no more than 12C outside right now. So it's possible that this doesn't happen everyday. On a warm day, that tank is busting at the chops to warm up beyond 26 and that fan is worth more than it's weight in gold to me..