Oase BioMaster Thermo 850


Up to 850 litres
Suitable for aquariums up to max. l 850
Dimensions (L x W x H) mm 240 x 240 x 535
Rated voltage 230 V / 50 Hz
Power consumption W 32
Power cable length m 1.50
Net weight kg 5.40
Guarantee (+ request guarantee) Years 3 + 1
Max. flow rate l/h 1550
Max. head height, metres m 2.20
Hose (quantity/length) 1 UNIT/4 m
Connection for hoses ø (inner/outer) 16 / 22 mm
Filter volume l 8
Pre-filter volume l 0.60
Suitable for freshwater Yes
Suitable for saltwater Yes

Oase BioMaster Thermo 850 is a very popular external filter from the German company Oase which also includes a heater. The Thermo 850 can cope with aquariums up to 850 litres of either salt or fresh water. The filter comes ready to use with in our opinion basic filter media. The included media consists of mostly sponge with a handful of hel-x 13 biomedia. Whilst this combination of media will be more than adequate for nearly all aspects of fish keeping there is room to improve. Oase have more than likely not gone overboard with the media knowing advanced hobbyist would prefer to choose their own.

Oase BioMaster Thermo 850 Features

An Easy to Clean pre filter that’s purpose is to extend the service intervals. If more porous media that’s capable of supporting Anaerobic, Nitrate removing bacteria the lifespan of this media becomes greatly extended.

A carrying handle which might not impress but, it makes life easier and we think its a nice touch.

The  400 watt heater which can not be described as built in as we have seen else on the web. The Oase BioMaster Thermo 850 just has ability to accommodate one. So its more of a place to put the heater which in this case is a standard glass heater. The heater fits and seals through a port in the filters head that tightens around the heater sealing firmly. The heater can be removed and used on its own and also the filter has a blank that when fitted the filter can function without the heater.

The Primer Oase BioMaster Thermo 850 has a built in primer as primers go operates well and seems to be well designed with a smooth efficient action. The shut off safety valve has a design unlike most other filters, it works well and has outlets that can also be positioned to suit.

Just A couple of things worth a mention about the Thermo 850.

You have to remember we are a an actual store that has a website so we do in store point out any issues or quirks with products. What we would make customers aware of instore is the danger associated with the heater.

Make sure that you never plug the heater in before the filter is primed and running. Otherwise the heater will switch on in a filter filled only with air. When you then prime the Oase BioMaster Thermo 850 the water will rapidly cool the heater and cause it to crack. Also if the heater is plugged in whilst the filter isn’t filled with water it will melt the media baskets.

Always unplug the heater at least ten minutes before servicing the BioMaster Thermo 850. This gives it time to cool down as there is no way of knowing if it is on or off so we must assume its on just to be safe.

Abyss Aquatics Top Tip

When you first set up the filter use the heater blank and put the heater in the fish tank. This way you can dial in the heater much easier without having to remove it from the filter to tweak. Once you are happy that the correct temperature is set fit it to the filter.

Oase BioMaster Thermo 850 Specifications.

  • Dimensions 240 x 240 x 480 mm.
  • Salt or fresh water.
  • Power consumption 40 watts.
  • Maximum flow 1550 litres pre hour.
  • Maximum head 2.2 metres.
  • Hose size 16-22 mm.
  • Hose length 4 metres, cut to suit.
  • Filter volume main 8 litres, Pre filter 0.6 litres.
  • Cable length 1.5 metres.
  • Weight 6 Kg.
  • 3 year warranty plus 1 year warranty extension with online registration.

What’s In the box

Aquarium Filter with an integrated heater, six carbon pre-filter foams, one 30 ppi filter foam, four 20 ppi filter foams, 2 units of Hel-X Biomedia, intake tube with inlet strainer, water distributor nozzle, spray bar, inlet and outlet adapters with flow control, tubing, fittings, heater adapter, and power cables.



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