Fish tanks direct carries the full line of Deep Blue Aquarium Heaters. Find the larges selection of Deep Blue Fish Tank Heaters on the market. Maximum strength quartz silica tube which is shatter resistant & more durable than conventional glass heater. "Easy set" thermostat provides precise and accurate thermal control. Includes gravel guard and suction mounting brackets for horizontal or vertical positions. Completely submersible. Safe and reliable for both freshwater & marine aquariums.