There are chillers that are made for this exact reason. If you goto a lfs they should be able to order you one. They can get up there in price so check places like marine depot or bulk reef supply for good deals
Living in Canada, I can't say I live in a "warmer climate". I have central air in my home and it keeps my tanks at a proper temp, but I was thinking of putting some tanks in my garage where there's a concrete floor since my home is rented and weight is a huge risk, especially with a 3 and 5 year old. Looks like most chillers are intended for larger tanks, or big setups with sumps and such. I just wanted to cool a few 20 gallon tanks lol.
For such a small tank blow air across the surface. You would be surprised what evaporative cooling can do. They also used to have small chiller probes. Basically a ceramic probe which for through a bulkhead attached to a fan and a heat exchanger. Don't know if they are still made, check drsfosterandsmith.com
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