Sku: 11230
Vendor: Marina

Marina Submersible Heater

$15.99 USD

Shipping calculated at checkout.

In stock!

Size: 6" 25w

6" 25w

6" 50w

8.5" 50w

8.5" 100w

10.5" 150w

10.5" 200w

10.5" 300w

Product variants

Product description

The Marina Submersible Aquarium Heater keeps your aquarium at a safe, stable temperature so your fish stay healthy and stress-free. Fully submersible with an adjustable thermostat and an easy-to-read temperature scale, it holds your chosen setting and switches on and off automatically. Built with high-impact safety glass and rated for both freshwater and saltwater, it comes in seven sizes from 25 watts for nano tanks up to 300 watts for large aquariums.

Always pair a heater with a thermometer so you can confirm your water temperature at a glance. Add our digital aquarium thermometer at Squeaky's Aquatics. Running a nano or betta tank under 5 gallons? Consider the pre-set Sicce Jolly 10W or 20W nano heater instead.

Why the Marina Heater

Adjustable thermostatSet your target temperature on the dial and the heater holds it, cycling on and off automatically.

On/off indicator lightA red light shows at a glance whether the heater is actively warming the water.

High-impact safety glassA tough, shatter-resistant glass tube stands up to knocks and bumps in the aquarium.

Fully submersibleMount it vertically or horizontally, fully underwater, and position it near good water flow for even heat.

Fresh or saltRated for both freshwater and saltwater aquariums.

Seven sizesFrom 25W nano heaters to 300W for large tanks, so you can match the heater to your volume.

Choose Your Size

Model	Wattage	Length	Heats up to
6 in, 25W	25 W	6 in	5.5 US gal (20 L)
6 in, 50W	50 W	6 in	10 US gal (38 L)
8.5 in, 50W	50 W	8.5 in	15 US gal (50 L)
8.5 in, 100W	100 W	8.5 in	30 US gal (114 L)
10.5 in, 150W	150 W	10.5 in	40 US gal (150 L)
10.5 in, 200W	200 W	10.5 in	55 US gal (200 L)
10.5 in, 300W	300 W	10.5 in	80 US gal (300 L)

Tank sizes are the ratings printed on each package. Note that the two 50W models differ: the compact 6 inch 50W is rated to about 10 gallons, while the longer 8.5 inch 50W is rated to about 15 gallons. As a rule of thumb, allow roughly 3 to 5 watts per gallon, and size up if your room runs cold.

Setup and Safety

Submerge the heater fully and let it sit unplugged for 15 to 30 minutes so the glass adjusts to the water temperature before you turn it on.
Place it near a filter outflow or powerhead so warmed water circulates evenly through the tank.
Set the dial, then check an aquarium thermometer after a few hours and fine-tune as needed.
Always unplug the heater and let it cool before removing it from the water, and never run it in open air.

Frequently Asked Questions

Can I set the exact temperature?

Yes. This is an adjustable heater with a temperature dial and scale. Turn the dial to your target, and the built-in thermostat cycles the heater on and off to hold it. We still recommend a separate thermometer to verify the reading.

Is it safe for saltwater?

Yes. The Marina Submersible Heater is rated for both freshwater and saltwater aquariums.

What is the difference between the two 50W versions?

They are rated for different tank sizes. The compact 6 inch 50W suits tanks up to about 10 gallons, while the longer 8.5 inch 50W is rated up to about 15 gallons. The extra glass length on the 8.5 inch model spreads heat over a larger volume, so choose it for a bigger or taller tank.

How do I pick the right wattage?

Match the size to your tank volume using the chart above, allowing about 3 to 5 watts per gallon. If your home is cool or your tank is large, choose the next size up for extra headroom.

My tank is under 5 gallons. Which heater should I use?

For nano and betta tanks, a small pre-set heater like the Sicce Jolly 10W or 20W is a better match than the 25W, since it is tuned for very small volumes.

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