HI Ron! Welcome to Fishlore! Unless you have a chiller, there are only temporary solutions. You could try freezing water in plastic bags and then placing the bags in the tank to slowly melt. Is your tank in front of a window? That might be another reason it gets too warm.
I didn't know there is such a thing as a "chiller" for aquarium tanks. Do you get it in your pet store? How does it look like? How does it work? Interesting, lol. So if one has a hot temperature where he/she lives, they don't need a heater, right? How, then, do they keep a stable aquarium temperature in such circumstances?
Gunnie, wow, this "chiller" alone is expensive. Saltwater tanks must be really costly! So, in saltwater tanks you don't use heaters? The water must be cold? What is the water temperature range for saltwater tanks?
Shabnam, as much as I love the sun and summers, I think I'd miss snow too! I love all 4 seasons - a little bit of everything, and the beauty of changing of seasons. I think I'd cook in a hot weather all year long! But yes, it's usually beautiful in the tropics, right? As you may have heard, Hurricane Katrina did so much damage in New Orleans, Louisiana - that living even in very low-level tropics makes it just scary. In the South of the Unites States people have hurricanes EVERY YEAR (literally). They lose their homes every year. They have nice warm weather all year long, but the price they have to pay is way too high I believe. I don't think I could handle that - losing my newly re-built home. It's terrible. That is why I prefer cooler but safer climates. Just a thought.
I know They're all probably dead by now. All the dirty and contaminated water undoubtedly got inside the tanks and poor fish just suffocated. Plus, it suffocated due to the lack of oxygen and lack of filtration - people have no electicity there, so no filters, heaters, or airpumps work. I'd be very disappointed if so much work, so many years of maintaining my tank and caring for all the fish in it, were destroyed just like that. It's sad. Also, the water that flooded the city was salty.
On the main topic, I should think some ingenuity would allow creating a device that pumps water through tubes in and out of the tank and through a bath of icewater. That's what I'd do before spending hundreds on fancy equipment. The degree of chilling could be controlled by the number of loops of tubing in the water.
Off-topic, but the comment about the fish surviving Katrina is actually a hugely important one. While it is my guess that those that got mixed into the cesspool of New Orleans waters would die swiftly, I'd think there were a few hundred salt-water tanks that got flooded with sea water in other parts of the Gulf. A few "exotic" fish getting loose in Gulf waters can be a recipe for ecological problems. Ask anyone who studies the oceans. They'll tell you of all sorts of problems created by huge ships discharging ballast water taken on in India and deposited in Gulfport. Don't forget the temperature of the flood waters from the Gulf would have been a very temperate 90 deg. F.
That couldl be one of the as-yet untold stories to come out of this disaster. :'(