Founded in 1902, DeLonghi is today one of Europe leading manufacturers of heating and air conditioning appliances and kitchen electrics. Further distribution of these materials by posting, archiving in public web site or database, or redistribution in computer network is strictly forbidden. Is it safe to add heater while fish are in the aquarium, and does anybody have any tips on how might instantaneous water heater go about it?? Thank you! Sorry! They danios. Alternately, the fan can be operated without heat for summer ventilation. You can run out of hot water if you use it faster than the heater is able to warm the water. What kind of corals inverts could use with these lights? have 10-gallon saltwater aquarium and have two.