Hi Garfieldfish,
You wouldn't want to do a 10 degree drop with livebearers, or most cichlids. But it works great as a trigger for cories. I combine the softer water, and colder water ideas...but using RO ice cubes. I put them right in the tank, not the filter. A typical drop in temp for my cories is 72 to 62. A few species are more sensitive then others. Don't go under 55. They'll start to do somersaults...or just lay on thier sides. Don't worry if this happens! Just warm them up, and they'll be fine. Small temperature changes are common in the wild. From shade to sunlight/surface to deeper water/ Rain/flowage from another source! Try it on your cories...They love it
