External heater for freshwater aquariums from 90 to 300 l

  • In-line heater integrated into the hose of the external aquarium filter, removing the need for a heater INSIDE an Aquarium
  • Easy installation: cut through the hose from the external filter that feeds the water back into the aquarium, insert the external heater in between, insert the plug and set the water temperature you want
  • The integration in the filter circuit ensures a very even distribution of the water temperature with an accuracy of +/- 0.5 °C and a switching interval of 1.0 °C in the aquarium
  • LED display of current and desired temperature. Interchangeable, screw-on (3/4'') hose connections for 12/16, 16/22 and 19/25 mm incl. hose securing. Total length 30.5 cm
  • Package contents: 1 in-line heater 300 W for aquariums from 90-300 l (80-120 cm) with hose connections for 12/16, 16/22 and 19/25 mm and cleaning brush
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Price: 50,30 €
Recommended retail price incl. VAT
You can find this item in your specialist and online shop
Product information

Most aquarium fish come from tropical waters and need water temperatures between 22 and 30 °C. In community aquariums with fish/invertebrates from different regions, a water temperature of 24-26 °C has shown to be effective. 30 °C is only suitable for some fish breeding (e.g. discus fish). Many shrimp species come from cooler waters and do not tolerate temperatures of 25-30°C.

The water temperature should be set with an "adjustable heater" which regulates the temperature automatically. For this purpose, there are rod-shaped heaters which are fixed in the aquarium (JBL ProTemp s) in various wattages and external heaters/in-line heaters which are integrated in the water-returning hose of an external filter (JBL ProTemp e) in two wattages. The advantage of external heaters is that it is one less product to be placed INSIDE the aquarium and the distribution of heat in the aquarium is more even. In addition, the digital display of the external heater always clearly shows the current water temperature. The outdoor heaters can of course also be operated with a separate water pump.

Undergravel heating is NOT used to set the water temperature. An undergravel heating cable ensures a better flow of water through the substrate of the aquarium, as the heated water at the heating cable rises and colder water flows into the areas between the heating cables. Thus nutrients are flushed to the plant roots and ensure optimal plant growth. Undergravel heating cables must always be supplemented by a "main heater" (JBL ProTemp s or e).



Art. no.:
EAN Code:
90-300 l
Volume packaging:
2.6 l
Gross weight:
500 g
Net weight:
400 g
Weight factor:
Packaging dimensions (l/h/w):
85/350/90 mm


Animal species: Armored catfish, Arowana, Axolotl, Barbels, Bettas, Bichirs/reedfish, Blowfish, Catfish, Cichlids (South America), Clawed frogs, Clawed shrimps, Crayfish, Crustaceans, Danions, Discus, Dwarf crayfish, Dwarf shrimps, Flowerhorn, Gill maggots, Gobies, Goldfish, Gouramis, Guppy, Juvenile fish, Killifish, Livebearers, Loaches, Mussels, Panchaxes, Rainbowfish, Snails, Spiny eels, Tetra, Veiltails, blood parrot cichlids, freshwater butterflyfish
Animal size: For all animal sizes
Animal age group: All aquarium and terrarium animals
Material: plastic (ABS) / glass
Colour: dark grey

Electronic label / illuminant

Mercury: No
Dimmable: No

Technical Data

capacity in litres:300 l
capacity from - to:90-300l
capacity tank length:120 cm
power output in Watt:300 W
Height:235 mm
Length:90 mm
Width:80 mm
voltage:240 V
What does the indication E-1 to E-8 on the display of my external heater mean?

As already described in the operating instructions, E stands for Error and indicates an error in the operation of the JBL PROTEMP external heater. Here you can see how each message can be easily solved.

E-1: Cause: Water temperature is at least 1 °C above the set temperature. Solution: Regulates itself when water temperature drops.
E-2: Cause: No water or air bubbles in the heater. Solution: Ensure that the heater is positioned as vertically as possible and that there is sufficient water flow.
E-3: Cause: Electronics defective. Solution: Can only be fixed by a specialist.
E-8: Cause: Temperature above 93°C. No water flow, or the inside is too soiled. Solution: Clean the inside of the heater with a hose brush (see chapter 8 Maintenance) and ensure sufficient water flow.

Does the alignment of the external heater matter during its installation?

Yes, because temperature measuring requires constant contact with the water. When installing, please pay attention to the flow direction marked by arrows on the heater housing. Attach the heater to the suspension loop provided for this purpose in a position as vertical as possible with the flow direction pointing upwards. This is the only way to ensure that the device is vented and that the temperature measuring functions properly.

What water pressure are the PROTEMP e in-line heaters designed for?

This device may only be used for heating aquariums in the private area. For this purpose, the in-line heater is connected to an external filter or a feed pump. These systems are unpressurised systems which only use the principle of circulation and do not build up any pressure, as the inlet and outlet also provide an additional drain and the impeller does not build up any water pressure when pumping. The use of accessories or parts not recommended by the manufacturer can lead to hazardous situations and a loss of warranty. Installations on pressure pumps or directly on water pipes are therefore not possible.

Where should you install the external heater?

First place the JBL PROTEMP e In-line heater on the outlet side of the external filter, before positioning the UV-C units, CO2 diffusers and other attachments. If this is not possible, you can still install the heater after the UV-C unit, but then only install diffusers behind it.

Blog (opinions & experiences)

JBL TV #61 Species-appropriate keeping of water turtles Part 1 – Setup and lighting

This part deals with the size of the terrarium, the setup, suitable substrates, creating water and land sections, the correct lighting with and without UV, how to use heat mats, and heating the water section.

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JBL TV #58: Which fish and plants fit into a 100 cm aquarium?

Which fish fit into a 100 cm aquarium and which fish are not suitable?

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Which fish and plants fit into a 80 cm aquarium?

Which fish fit into a 80 cm aquarium and which fish are not suitable?

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JBL TV #54 The right water temperature – all the facts about temperature in the aquarium

A conversation with the chief biologist of the Sealife Centre in Speyer about issues which can arise in some water temperatures.

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JBL TV #49: Saving energy in the aquarium - reducing costs made easy

Yes, we can make energy savings in our aquarium, but not where most people think! In this video we show exactly where and how to save electricity costs.

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JBL TV #24: Aquarium heaters and aquarium coolers

What temperatures do our aquarium inhabitants have in the wild? How can you heat and cool your aquarium simply and effectively?

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JBL TV #19 Part 1: Aquarium Set-Up - Aquarium Technology - Where Do You Put The Heater And Filter?

Installing aquarium technology, where do you put the heater and filter?

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The JBL Intern - Aquariums in the Company

When I first entered the administrative offices, I was very impressed by the display aquariums in the boss's office and in the various conference rooms.

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Heating in the aquarium. Heating rods vs. outdoor heaters

Our houses aren’t the only things to need heating. Our fish habitats, or aquariums, also need to be kept at a constant, feel-good temperature. This can vary from aquarium to aquarium and needs to be individually regulated.

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Video: JBL PROTEMP e External Heater for Aquariums - Keeping Electricity and Technology Outside the Aquarium

External heaters remove the need for bothersome heating elements in the aquarium and are safe because the electricity stays outside. The installation could not be easier.

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Display Accuracy vs. Measuring Accuracy - Different Results When Measuring Temperatures

You may find the differences that can arise when measuring the temperature with different measuring instruments and methods, confusing. Most people tend to trust a digital device more than an analog device. Is this justified?

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JBL PROTEMP e - Heating The Inside From Outside

Nobody likes a heater in an aquarium: it’s as attractive as an old stove pipe and contains a full 230 volts. The alternative is as simple as it’s logical:

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Additional product information and downloads

safety instructions

  • safety instruction for technical devices
    • Filename:
spare parts
Customer reviews


Overall rating: 4.9
23 public review(s) for this product.

0 Reviews

23 more reviews in other languages

23 Reviews in other languages

D. Langenfeld - German

Gute Heizung außerhalb des Aquariums. Lässt sich mühelos an alle gängigen Aussenfilter montieren

F. Carroll - German

Perfekt für alle die keine weitere Technik im Aquarium haben wollen. Einfach Montage und Bedienung. Bin rundum zufrieden

K. Maessen - Dutch


Zeer blij met deze nieuwe verwarming. Gemakkelijk om te installeren op mijn Cristalprofi filter.

Er zijn aansluitingen voor diverse apparaten diameters van slangen voorzien (12/16-16/22-19/25mm).

Gewenste temperatuur kiezen en klaar!

Je ziet en voelt aan alles het Jbl kwaliteit is. Top!


LadyDiscus - Polish

Aquawelten - German

Bei mir laufen mittlerweile 2 E300 Aussenheizer an jeweils einem Becken. Digital ablesen, mit einem Klick einstellen. Einfach grandios. Weniger Technik im Becken gefällt mir dabei auch sehr gut

Aquarium.by.bddnk - German

Nutze ich bereits das zweite mal und bin sehr zufrieden mit dem Prodult 👌🏼😍

G.E.P.P. - French

Un chauffage externe fiable et solide !

Je l'utilise avec les robinets double raccord rapide sur un JBL CRISTAL PROFI e402 pour une cuve de 60 litres.

Je le trouve plus esthétique qu'un chauffage interne. Celui-ci est caché dans le meuble avec tout les accessoires techniques.

Parfait 👌

D. Bräuer - German

Eigentlich eine sehr sehr geile Sache,allerdings ist es schade das es keine vernünftige Halterung gibt ich möchte mir nicht extra einen Haken in den Schrank schrauben, um den Heizer an diesem Henkel aufzuhängen

Aquawelten - German

Für mich die beste Lösung auf dem Markt. Wer einen Aussenfilter nutzt, sollte von diesem Heizer unbedingt gebrauch machen.

Aquariuana - German

Die Heizung ist Klasse! Habe jetzt endlich keinen unschönen Heizstab mehr im Becken :)

Läuft ruhig und heizt das Wasser schnell aus. Nutze diesen in einem 60L Becken.

Achtet nur darauf die Heizung mit der Ösen aufzuhängen um den Schlauch zu entlasten und das die Heizung vertikal hängt.

shrimpscapes_ - German


Ich weiß gar nicht so recht was ich sagen soll außer dass ich einfach nur Begeistert von diesem Produkt bin.

Super schnell eingebaut. Heizt schnell auf wenn man beim Wasserwechsel mal etwas kälteres Wasser einfüllt. Keine hässliche Technik mehr IM Becken und er hält die eingestellte Temperatur ohne wenn und aber! Und das bei diesem Preis.

bennys riff welt - German

Echt der Hammer

Schnell eingebaut und Läuft eins A will keine andere Heizung mehr haben !

D. Van Hengel - Dutch

I have the protemp 300 on my 160 liter aquascape and this is the best heather I ever had. Always accurate temperature and no Heather needed in the tank, because this is a Inline product, so you put in between the Inline hose and the water is on temperature in no time

dr_scaper - Polish

the best and very comfortable as well as precise external heater I have had. I recommend this product

dr_scaper - Polish

the best and very comfortable as well as precise external heater I have had. I recommend this product Dr. Scaper

ShrimpPuddle - German

Ein Heizer der schon lange bei mir in Betrieb ist, ich bin sehr zufrieden mit Ihm, sowohl was die Heizleistung, als auch die Genauigkeit angeht. Und vor allem nimmt er keinen Platz mehr im Aquarium weg. ✌🏻

aquaristik_4_life - German

Idealer Heizer für alle, die wenig Platz im Aquarium haben oder so wenig Technik wie möglich innerhalb des Aquariums / Aquascapes haben wollen (wegen der Optik).

Ich verwende seit ca. 2 Jahren den e300 Heizer in Kombination mit dem e902 Filter und Proflora Inline Diffusor an meinem 125l Becken und bin sehr begeistert.

-->Gebrauchsfertige Auslieferung. Es ist alles dabei (Heizer, Reinigungsbürste, versch. Anschlüsse für unterschiedliche Schlauchdurchmesser).

-->Genaue Temperanzeige (0.1°C - Schritte) + Temperatureinstellung (0.5°C - Schritte)

-->Seltene Reinigung notwendig

-->Nicht hörbar

-->Warnungen bei Temperaturabweichungen

-->Gute Ersatzteilversorgung

Viele Grüße


(Schaut gerne auf meiner Instagram Seite vorbei :-))

tefanDerksS - Dutch

I love this product!

Perfect for aquascapers. I don’t like that ugly heater in the tank. With this inline heater that problem is fixed!

justaquascaping - German

Ich liebe den Heizer. Allein die Größe ist bei begrenztem Platz im Unterschrank etwas hinderlich wenn weiteres Zubehör wie ein Inline CO2 Diffusor und Schnelltrennkupplungen verwendet werden.

Bögen oder 45° Adapter für die Anschlüsse und eine Click-Aufhängung zum anschrauben an den Schrank wären praktisch, oder aber eine leichtere Mini-Version mit 100W.

Eigentlich 5/5, aber Aufgrund der Größe nur 4/5 Sternen.

Dutch aquascaper - Dutch

Perfect for aquascapers. I don’t like that ugly heater in the tank. With this inline heater that problem is fixed!

Phils_waterplants - German


Sehr genauer Heizer mit Digitaldisplay. Lässt sich kinderleicht einstellen und heizt unauffällig im Unterschrank. Heizt nach dem Wasserwechsel innerhalb von Minuten auf die gewünschte Temperatur auf.

Für mich gibt es nie wieder einen anderen Heizer

der_ aquariumschrank - German

Ein Super Produkt ich kann es nur empfehlen kaum noch Technik im Becken:)

Aquaklausi - German

Für mich die Perfekte Lösung um auch große Aquarien ohne bzw mit sowenig Technik wie möglich im Becken zu betreiben.

Ich habe den Pro Temp 300 bereits an 2 Aquarien verbaut und bin super zufrieden.

Die Möglichkeit verschiedene Schlauchdurchmesser anzuschließen macht den Heizer super flexibel.

Ich würde jedem Aquarianer oder Aquascaper eine ganz klare Empfehlung aussprechen.

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