JBL hydrometer
Hydrometer for saltwater aquariums

  • Suitable for use in scientific contexts: hydrometer with stable stand, thermometer and measuring vessel
  • Convenient to use: half fill the measuring vessel with saltwater, insert the clean hydrometer, read off values after 1 minute.
  • Reading accuracy of 0.0005 units.
  • Thermometer and built-in temperature correction scale, transport cylinder (height 33.5 cm) serves as measuring vessel
  • Package contents: 1 density measurement device for saltwater, hydrometer with thermometer + measuring vessel
Find out more
Recommended retail price incl. VAT
Available from your specialist dealer.
Dealer close to you
You can find this article at your specialist shop and online
Product information

Nature at Home – Home for Fish and Plants
Lesser animals and corals need to feel as much at home in the aquarium as they do in the wild. Convert your aquarium water into biotope water and protect these animals by using natural substances.

Density in saltwater aquarium
When aquarium water evaporates salts remain, which increase the density in the aquarium. To prevent damage to fish and plants it is important to check the density regularly and to take any appropriate steps.

Suitable for use in scientific contexts
The JBL hydrometer has a reading accuracy of 0.0005 units. Its octagonal stand makes it stable and it is screwed onto the vessel. The hydrometer has an integrated thermometer and a temperature correction scale.


JBL hydrometer

Art. no.:
EAN Code:
24,5 cm
Volume packaging:
1.840 l
Gross weight:
180.000 g
Net weight:
120 g
Weight factor:
Packaging dimensions (l/h/w):
75/390/70 mm
The hydrometer is broken. It contains a red liquid. What does the red liquid consist of and is it toxic?

The hydrometer doesn’t contain any mercury. The liquid contains an alcohol solution with colouring. It is non-toxic. Both ingredients are quickly broken down by the bacteria in the aquarium. Furthermore the diluting effect should be taken into consideration. The silvery pearls are an iron compound and are therefore harmless. Simply siphon them out of the aquarium.

What range does the scale of the hydrometer cover?

A reading accuracy of 0.0005 units makes the hydrometer very accurate.
The built-in thermometer, which covers a scale from 9°C to 32°C, and the temperature correction scale gives you the highest precision. The density is determined in a range of 1016 to 1028.

Blog (opinions & experiences)

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?

Find out more

Inaccurate water tests – or did I do something wrong after all?

In the aquarium scene we often hear people talking about “accurate” and “inaccurate” tests. But mostly they mean a rougher or finer scaling of the output values.

Find out more

Keeping an eye on the most important water values

Professional water analysis sounds very expensive. But the professional water testing in your aquarium or pond at home also works on a high level and above all it is simple and inexpensive.

Find out more
Laboratories and calculators

Water Analysis Online Laboratory

Enter your water parameters and get an in-depth analysis of your values in a matter of seconds. You enter your water values – and we analyse! Here you have the opportunity to enter the measured water values directly into the JBL Online Laboratory. This will analyse your values and explain and submit corrective measures.
Reference guide (Themeworld)

Marine water

There is a solution to almost every problem! And the hardest part is finding the cause of the problem.

Deficiency symptoms

Here’s how to prevent deficiency symptoms in fish and plants

Marine water treatment

What maintenance does your marine aquarium need?

Daily care

How much daily or weekly care is involved? What are the basic maintenance measures for your aquarium?

Marine water - the water

What exactly is marine water? What is so special about marine water? How to create perfect marine water?

Installation technical items

How and where in the aquarium do you fix and install technical items? Tips and tricks for the installation of all technical aquarium products

Marine water - technical items

What is the difference between a marine and a freshwater aquarium? What is especially needed for a marine aquarium?

Heating and cooling

Why is 25 °C ideal? This is how to heat or cool aquarium water

The marine aquarium

Holiday at the coral reef - in your own living room! Marine aquariums are the most exciting branch of aquatics


safety instructions

  • safety instruction for accessories
    • Filename:

A word about cookies before we continue

The JBL Homepage also uses several types of cookies to provide you with full functionality and many services: We require technical and functional cookies to ensure that everything works when you visit this website. We also use cookies for marketing purposes. This ensures that we recognise you when you visit our extensive site again, that we can measure the success of our campaigns and that the personalisation cookies allow us to address you individually and directly, adapted to your needs - even outside our website. You can determine at any time - even at a later date - which cookies you allow and which you do not allow (more on this under "Change settings").

Are you over 16 years old? Then confirm the use of all cookies with "Noticed" and you are ready to go.

Choose your cookie settings

Technical and functional cookies, so that everything works when you visit our website.
Marketing cookies, so that we recognize you on our pages and can measure the success of our campaigns.