Marina Submersible Pre-Set Heater 50w

A 50W submersible aquarium heater for tanks up to 38 litres, 22cm long

£30.19

· tracked · UK mainland estimate · 14-day promise

UK delivery £2.99 · free over £39

Secure checkout by Stripe · Card, Apple Pay & Klarna

Never switch it on out of water, and buy a thermometer

A glass heater run dry, or switched on in air during a water change, can crack — so unplug it and let it cool if the level is going below it. And a heater's dial tells you what it has been asked for, not what the water is actually doing; a separate thermometer is a couple of pounds and is the only thing that tells you the truth. In a tank as small as 38 litres, temperature swings faster than in a big one, so it is worth checking.

Secure checkout

Tracked delivery

Easy returns

Easy to use, made to last

Why we chose it

The pilot light is the reason to choose this over a cheaper one. A dead heater looks exactly like a working heater until the fish tell you, and in a small tank that is a short conversation. Matching 50 watts to 38 litres is the other half — buy for the water, not the price.

— Matt, founder

Specifications

Material: durable high-impact glass, it’s built to last under normal aquatic conditions
Brand: Marina
Length: 22cm
Material: durable high-impact glass, it’s built to last under normal aquatic conditions

Full description

Small tanks are where heaters go wrong most often, because the temptation is to fit something more powerful than the water needs. A 50 watt heater is matched to about 38 litres, and in a tank that size an oversized heater will overshoot before the thermostat can catch it — which in a small volume of water happens fast.

This one is 22cm long, submersible, in impact-resistant glass with waterproof sealing, and it works in fresh or salt water. The temperature dial sits where you can reach it, the settings are printed to be read through water, and an on/off pilot light shows whether it is calling for heat. There is a bumper guard to keep fish off the glass and a bracket with suction cups to hold it in place. It is CSA approved.

50 watts, for aquariums up to 38 litres
22cm long
Fresh or salt water
On/off pilot light and an accessible set dial
Bumper guard and a suction-cup bracket
Impact-resistant glass with waterproof sealing

Never switch it on out of water, and buy a thermometer. A glass heater run dry, or switched on in air during a water change, can crack — so unplug it and let it cool if the level is going below it. And a heater's dial tells you what it has been asked for, not what the water is actually doing; a separate thermometer is a couple of pounds and is the only thing that tells you the truth. In a tank as small as 38 litres, temperature swings faster than in a big one, so it is worth checking.

Who it's for: small tropical tanks, quarantine and hospital tanks, and anyone replacing a heater that has quietly stopped working.

Delivery

Tracked UK delivery — your estimated arrival date is shown above and updates automatically. Standard delivery £2.99, and free on orders over £39. Full details on our delivery information page. Delivery information

Returns

14 days to change your mind, no interrogation. Items need to be unused (sensory products unopened, for hygiene). Full details on our delivery & returns page.

Payment

Secure checkout by Stripe — cards, Apple Pay, Link and Klarna. We never see or store your card details.

Common questions

What size tank is it for?

Aquariums up to 38 litres, at 50 watts.

Can I use it in a marine tank?

Yes. Marina list it for fresh or saltwater aquariums.

How long is it?

22cm.

Can I leave it on during a water change?

No. Unplug it and let it cool if the water is going below it — a glass heater switched on in air can crack.

What size is it?

22cm. Every measurement we hold for this product is in the specifications above.

How long does delivery take?

Your estimated delivery date is shown above and updates automatically. UK orders are sent tracked — standard delivery is £2.99, and free on orders over £39.

How do I track my order?

As soon as your order is dispatched we email you a tracking link, so you can follow it all the way to your door.

What is it made from?

durable high-impact glass, it’s built to last under normal aquatic conditions. Full specifications are listed above.

What if I need to return my order?

You have 14 days from delivery to change your mind. Just email us with your order number and we’ll send the return steps the same working day — see our delivery & returns page for details.

Why buy from Giddy Pets?

Carefully selected by pet ownersEvery product is chosen and quality-checked by people who actually live with dogs, cats and small pets.
Tracked delivery on every orderUK delivery with tracking as standard — and it’s free when you spend over £39.
UK customer supportReal, UK-based humans read every email — usually Matt, the founder. No bots, no ticket numbers.
Easy returns14 days to change your mind, no interrogation. If it’s not right, we’ll make it right.