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Established 1989
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JBL hydrometer

Code: 6140800
  • £27.09
  • RRP £37.20
Item in Stock   |   Usually dispatched within 24 hours

Precision glass spindle and measuring vessel for measuring the salt content (density) in marine water aquariums

  • 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 and therefore also suitable for scientific purposes. Reading range of density from 1.016-1.028 (recommended range: 1.021-1.025)
  • Thermometer and built-in temperature correction scale from 9 to 32 °C. Transport cylinder (height 33.5 cm) serves as measuring vessel
  • Package contents: 1 hydrometer for marine water with built-in thermometer + measuring vessel with stable stand

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. In a marine water aquarium, this includes the right water values, the right light, a varied and species-appropriate diet and of course the right salinity. Density in marine water aquariums
When aquarium water evaporates, salts remain and they increase the density in the aquarium. To prevent damage to fish and invertebrates it is important to check the density regularly and to take any appropriate steps. Density is temperature dependent:
At 25 °C, hydrometers indicate exactly the right density. Higher temperatures will require a correction factor, which is indicated in the JBL hydrometer on a scale next to the built-in thermometer. At 30 °C, for example, 0.001 needs to be added to the indicated density of, say, 1.022. The correct density at 30 °C would therefore be 1.023. At water temperatures below 25 °C a correction factor would have to be subtracted, e.g. at 20 °C 0.001 would have to be subtracted from the displayed density value. So if this is 1.025, the real density at 20 °C is 1.025 minus 0.001 = 1.024. If the water temperature in cold marine water aquariums is 15 °C, a correction of -2.5 ° needs to be made.

Next Day Shipping Upgrade - Cut off Midday (12 pm)

Please Note: We only deliver pond plants on our own delivery vehicles!

The highlighted area on the map below is where we deliver on our own vehicle! Unfortunately, if you are not in one of these postcode zones we are unable to deliver certain items such as plants, small glass items and selective other products.



We offer a few different delivery options depending on the size and value of your order.

Orders over £50 qualify for free mainland UK delivery which will arrive within 3-5 working days of the order being processed.

Residents of Northern Ireland, please provide your EORI or XI Number.

If you do not have one, please follow the information at

Orders Below £50 in Mainland UK will be charged a standard delivery fee of £5.99.

Additional Shipping Charges

For any orders that do not include Aquariums, the below is charged:

Next Working Day Parcel Delivery to Mainland UK - £7.99 OR £2.99 if the order is over £50

Standard Parcel Delivery to Northern Ireland £8.99

Standard Parcel Delivery to Scottish Highlands & Islands £9.99

Standard Parcel Delivery to Jersey & Guernsey £12.99


For all Aquarium deliveries (Excluding biOrbs & Smaller Aquariums), the below is charged:

Next Working Day Pallet Delivery - £20

2 Hour Booking Slot Pallet Delivery - £20

Pallet Delivery to Northern Ireland - £38

Pallet Delivery to Isle of Wight (PO36 and Above) and Scottish Highlands (AB, PH, IV1-36, IV63, KW1-14, KY, PA21-41) - £38

Pallet Delivery to Southern Ireland - £48

Pallet Delivery to Offshore postcodes (KA27-28, PA20, PA42-49, PA60-90, ZE, JE, GY. IM) - £70

Pallet Delivery to the Scottish Isles (IV40-56, KW15-17) - £90

Pallet Delivery to Outer Hebrides (HS) - £120

Payment Methods

We accept all major Credit and Debit cards, and these are processed via a third party payment gateway called Opayo. 

We also accept payments via PayPal and PayPal credit. 

Also, you can pay using Android and Apple Pay if you are using a compatible device. 

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.


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JBL Specification
Gross Weight 180 g g
Net Weight 120 g g
Packaging Dimensions (L X H X W) 75/390/70 mm
For Animal Species Marine fish, Corals, molluscs
For Animal Size For all animal sizes
Animal Age Group All aquarium fish
Volume Habitat For all aquariums
Material glass / metal (aluminium)
Colour white / transparent / green / red
Contact us with any questions you have about this product