The Finnex THD Series Titanium Heater Elements deliver dependable aquarium heating in a sleek, streamlined design. Each THD heater uses durable titanium paired with an internal industry-standard quartz sleeve for steady, consistent heat output. The THD line is your trusted standard, while the TH Series pushes the limits with extended quartz elements for maximum durability and lifespan. Safety First: High-Temp Heater Guards Every Finnex TH and THD heater comes equipped with a high-temperature protective heater guard. These guards create a vital barrier that prevents fish, plants, and corals from making direct contact with the hot tube surface. This reduces accidental burns or injuries, especially for larger or curious species, while allowing full water flow around the heating element for even, stable temperature control. How the TH and THD Compare Both series use premium titanium for unmatched corrosion resistance and performance. The THD matches industry standards with an internal quartz sleeve and compact tube. The TH Series steps up with a thicker diameter and longer heating tube, giving greater surface area for stable heat distribution and lower cycling stress — which means longer life and greater reliability. When choosing Finnex, you know the THD is built to outperform standard glass heaters, while the TH is the go-to for demanding aquarists who expect the best. Model Voltage Amps Diameter Length Volume THD-300S* 120V 2.7A 0.62" 11.02" 40–80 Gal THD-500S 120V 4.5A 0.62" 11.02" 70–125 Gal THD-700S 120V 7.3A 0.74" 12.99" 110–200 Gal TH-300S* 120V 2.7A 0.75" 10" 40–80 Gal TH-500S 120V 4.5A 0.75" 13.8" 0–130 Gal TH-800S 120V 9.0A 0.75" 16.5 140–265 Gal * While the THD-300S titanium tube is longer than the TH-300S, the TH-300S — like the entire TH Series — features extended quartz glass sleeves and coils within for premium longevity and superior heat distribution, making it the premium choice. Titanium Heating, Trusted Since 2001 Finnex has specialized in advanced titanium aquarium heating solutions since 2001 — over two decades of engineering reliable, innovative heaters trusted by hobbyists, breeders, and professionals around the globe. When you choose Finnex, you’re choosing proven performance, industry-leading safety, and unmatched durability backed by years of dedicated aquatic expertise.
