Ocean GEOtronic regulators keep aquarium temperatures consistent year-round. The regulators create a temperature difference and a heat flow from a direct electric current for both heating and cooling, enhancing the growth of corals and assisting in fish reproduction. Great for saltwater tanks, they have no moving parts other than fans, and all six models are made of corrosion-resistant materials that do not need specific maintenance. The Ocean series comes in several models including: Ocean 60, 150, 300, 400, 600, 900, the 900 model is great for tanks up to 237 gallons, while the Ocean 60 model can handle a tank up to 18 gallons. The Ocean 60 pricing starts at $700, and these are in select retailers now.