how to lower tank temp?

[Swimfins]

If you put your filter into a cooler chest, with a refrigerated (not frozen) gel or ice pack, in an 80 degree or so room, you only need change the pack once a day.
Keep one in the fridge ready to replace the one in the cooler. Easy. Although a/c is the best option for human inhabitants too

 

[f8ldzz]

After reading this thread, I decided to try a fan.
We got a baby Vornado, and I managed to get it blowing into the top.
Holy Moley!
I can't believe this works so well...maybe too well.
Tank temps are typically easily over 80F.
Average is more like 82F to 84F.
Turn on the lights, and it will easily get over 85F.
At times, the temps get closer to 90F.
With the fan, temps dropped under 80F easily.
With the lights on, it will do 76F to 78F easily.
With the lights off, it will drop to under 76F quite easily.
Fan is set to "middle" setting.

Now the bad part...water evaporation is quick!
On the 10G, it'll easily drop 1" on the water level in half a day.
I'd be lucky to get 1/4" water level drop in a week without the fan.

 

[Swimfins]

Another thing to consider with evaporation:You might need to up water changes, rather than just add water to the tank. By replacing water, you are not diluting the toxins that can accumulate if you just replace the water. The fan sounds like a good solution. Where do you live anyways? lol

I was thinking more in the line of big tanks, I've been asking around my lfs what to do in summer for my 66g as I don't want to turn off my pc compact for the plants, and they gave me the above suggestion. But, I think I'll get a/c, for myself too.