In short a chiller is air conditioning for your aquarium water. If you are in a place where ambient room temps are very high, or you have serious reef style lighting. Much more common on reef set-ups than planted tank setups.
A Sump, is a basically a container to hold water, and equipment (heaters, pumps, probes,etc...) that usually sits under you tank, and is part of a water circulation or filter system. Also more common in Reef set-ups than planted tanks, but much more common than chillers.
A Sump, is a basically a container to hold water, and equipment (heaters, pumps, probes,etc...) that usually sits under you tank, and is part of a water circulation or filter system. Also more common in Reef set-ups than planted tanks, but much more common than chillers.