Finnex Titanium Aquarium Heater THD Series, Slim: 300, 500, 700 watts

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.

The Titanium Advantage

Titanium is trusted by experienced aquarists for its unique combination of strength, corrosion resistance, and thermal efficiency. Unlike glass, titanium won’t shatter, making it safer in tanks with active fish or large species. Its superior heat transfer allows for fast, even heating without hotspots — critical for sensitive reef tanks and delicate freshwater species.

• Marine & Freshwater Safe: Naturally corrosion-proof, titanium thrives in saltwater setups where other metals fail.
• Efficient Performance: Fast response means stable tank temps, less energy waste, and healthier fish and corals.
• Built to Last: With no fragile glass casing, titanium heaters endure heavy use and bumps without cracks or leaks.

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.

*Heating Element Only.  Controllers sold separately.