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The importance of using Reverse Osmosis (RO) water for use in an aquarium cannot be over emphasised and so D-D have a full range of high quality Reverse Osmosis Units for all applications.

Reverse osmosis water is essentially free from chlorine, nitrates, phosphates and heavy metals and is an ideal base for making up salt solutions or for freshwater aquariums or replacement of evaporated loss.

Tap water is generally full of these pollutants and the effect on your aquarium can be quite severe depending on how bad the water is in your particular area, fueling algae and diatom blooms which must be then maintained by chemical methods.

D-D have two available options on the RO units, 50GPD and 125/150GPD membrane. 

3 Stage System

The three stages consist of:

1 - A 10" 5 micron pre-filter to remove sediments and particles from the mains water to protect the membrane from clogging and extend it's life. This is housed in a clear membrane to allow you to monitor the colour and life of the disposable element. We recommend that this low cost filter element is changed at a maximum interval of 6 months.

2 - A 10" 10 micron block carbon filter. This carbon filter is designed to remove the chlorine from the water. In the UK the chlorine levels are generally not high however we still recommend that you change this element every 6 months.

3 - The RO Membrane and housing. This stage holds the membrane itself. All D-D membranes are high quality thin film membranes. 

Available sizes

Product Code RO50 - 50 Gallon Complete R.O. Unit
Product Code RO150 - 125-150 Complete Gallon R.O. Unit

Plug & Play

All D-D RO Units come complete with the following:

  • Flow restrictor with integral membrane flushing valve.
  • Self-piercing tap connector.
  • Threaded tap connector.
  • 2m of 1/4" RO tubing in white, blue and orange.
  • Saddle valve for the waste pipe return.
  • Filter Spanner.
  • Full instructions.



  • Height: 39cm
  • Depth: 13cm
  • Width: 35cm

Output Rate

When choosing the size of RO unit remember that the output flow will vary greatly with temperature and mains pressure. The 50/125-150 gallons quoted on the membrane refers to US gallons at a standard pressure and temperature of 25C. In practice the supply water is never this warm and therefore the flow rate is reduced.

If as a rule of thumb, on any manufacturers RO units, if you expect to get half of this tested output in practice then you will not be disappointed.

Fitting of a D-D Booster Pump will increase the pressure up to 8 bar which will overcome any temperature and pressure variations and normally produce the full membrane flow rate. This is particulary useful if you live in a low pressure area or off the mains water supply.