Zoo Med Repti Therm Under Tank Reptile Heater 16 Watts, 12 Inch Long x 8 Inch Wide, 30-40 Gallons, Pack of 4 Review (2026)

What this pack is and who buys in bulk

Zoo Med's Repti Therm under tank heater is a thin, adhesive-backed heating pad that sticks to the outside bottom of a glass terrarium to create a warm zone on one side of the enclosure. This listing bundles four of the 16 watt, 12 by 8 inch pads together, which is aimed less at a single-pet keeper and more at breeders, rescues or anyone running multiple 30 to 40 gallon enclosures at once, since buying four together typically brings the per-unit cost down compared with purchasing one at a time. For a household with just one reptile, four heaters is more supply than needed, and a single pad or a smaller 2-pack would be the more sensible purchase.

Build and how it heats the tank

Each pad uses a solid state nichrome heating element and carries UL and CUL approval, and Zoo Med rates this size for 30 to 40 gallon glass terrariums specifically, not wood, plastic or acrylic enclosures, since the heat transfer and adhesive are designed around glass. Small rubber feet included with the terrarium setup are meant to lift the tank slightly so warm air can escape from underneath rather than building up against the stand. Zoo Med positions this as a 24-hour primary or secondary heat source, and recommends placing it on one side of the tank rather than the center, so the reptile has a clear thermal gradient to move across rather than a uniformly warm floor.

Installing and running four heaters

Each pad adheres permanently once applied, so placement should be planned before sticking it down, aligned with the intended warm side of each enclosure. Because there are four separate heaters in this pack, a keeper running four tanks needs either four separate thermostats or a multi-channel controller that can handle more than one probe and outlet, since each pad benefits from its own temperature monitoring rather than sharing a single thermostat across enclosures with different setups. Zoo Med describes the heat output as regulated rather than freely adjustable by the keeper, which is part of why many keepers still add an external thermostat, mainly for the added safety margin and per-tank temperature control rather than because the pad runs unchecked.

Value and how it compares

In the site's under tank heater guide, this pack ranks first of seven, ahead of single-unit options like Zoo Med's own 8 by 18 inch pad and a smaller 3-pack sized for tanks up to 5 gallons. The main advantage here is the bulk pricing on a well-established, UL-listed heater from a brand widely used in the reptile hobby, rather than any difference in the heating technology itself compared with Zoo Med's other UTH sizes. Against a generic iPower heating pad, Zoo Med's build and UL approval carry more weight for keepers who prioritize a known safety record over the lowest price per pad. Buying four together also means a rack or multi-tank setup keeps a matched, identical heater on every enclosure rather than mixing brands or wattages across shelves.

Who should buy this pack

This 4-pack fits keepers or small operations running multiple 30 to 40 gallon glass terrariums who want a consistent, UL-approved heat source and are prepared to pair each pad with its own thermostat. It is not a good fit for a single-reptile household, which will end up with three unused heaters, or for anyone with a wood, plastic or acrylic enclosure, since Zoo Med specifies glass-only use for proper heat transfer and adhesion. Shoppers who only need one heater are better off buying a single unit or a smaller 2-pack rather than paying for pads they will not use for years.

Frequently asked questions