This is mixed bed and colour changing resin. Both cation and anion resins are combined in this one bag. Colour changes as the  resin is used up.

Sold in 570 g or  Bulk ; 3.75 kg (5 litre)   sealed bags – 570 gram is  enough for one 10″x2.5″ cartridge

The anion resin is a Type I strongly basic gel resin with an indicator dye that changes from blue to light brown as the resin exhausts.


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Description – Mixed Bed DI  Resin Colour Changing MBD-30

Benefits of Mixed Bed DI Resin( Colour Changing Deionising Resin) 

  • You will know when the media is exhausted ( changes from blue to light brown)
  • Will warn you from eminent TDS creep
  • Will ensure that when you receive the resin it is in good condition

image fish

We recommend colour changing resin  simply because  it will physically change colour as it gets exhausted.  That allows you to monitor the consumption of the DI resin and know when to change it out.  If you have a TDS meter we still recommend colour changing resin as it will let you know when to monitor your TDS meter for when TDS starts creeping through the DI resin.  

DI Resin is necessary to reduce Total Dissolved Solids (TDS) to zero and is the last stage of an RO/DI unit. Resin is sold in economical bulk bags as well as single use pouches. The resin is designed to be used with one of our refillable DI cartridges. This refillable design saves a small fortune over proprietary sealed cartridges.

This is mixed bed and colour changing resin. Both cation and anion resins are combined in this one bag. Colour changes as resin is used up. We also offer bulk Anion and bulk Cation resins.

 RESINTECH MBD-30 is a self indicating mixed bed resin. It is a mix of nuclear grade hydrogen and hydroxide form resins. The anion resin is a Type I strongly basic gel resin with an indicator dye that changes from blue to colorless as the resin exhausts. The cation component is a strong acid sulfonated polystyrene gel type cation exchange resin. During exhaustion, as the indicator dye changes colour, the appearance of the mixed bed changes from a blue to light brown colour. Many manufacturing processes require high purity water for washing, rinsing and test purposes. Not all processes requiring demineralised water need the ultimate quality. However, they may require multi-megohm resistivity water. RESINTECH MBD-30 is designed to provide demineralised water with a resistivity in excess of 10 megohm. It is specially intended for use in cartridge applications with clear (see through) housings. Such systems are typically designed without meters and rely on the changing colour of the mixed bed resin to indicate exhaustion.  The actual quality that is obtained depends on the manner in which the cartridge is configured. A constant supply of high purity water can be obtained by using two cartridges in series.


Deionisation removes the  contaminants like silicates  that have passed through the RO membrane.  Deionising your RO water is especially important for Marine aquariums. Silicates and other ions in the aquarium water can cause  many problems like algae and diatoms. Encrusting diatoms are most dangerous in reef tanks since they will first start to grow at the base of corals and move upward. They will cause the corals to recede and in a matter of a few days can kill the colony. 

Many species of these kinds of algae exist in your aquarium and can harm your fish merely by blocking light and monopolising space. Should they become too prolific, the dead and decaying population will quickly increase toxin levels and reduce the amount of dissolved oxygen available for your fish and invertebrates. 

Colour changing DI resin- changed from blue to brown when exhausted.

Colour changing DI resin- changed from green to purple when exhausted.


Optimising the life of your colour changing  Mixed Bed DI Resin

  • Ensure optimal operation of your RO membrane. The higher your membranes rejection rate ,the fewer TDS ( Total Dissolved Solids) your product water will contain, resulting in longer lasting resin. The best way to keep the membrane rejection rate up is to monitor and change your prefilters appropriately as well as maintain at least 350 kPa at your RO system.
  • Ensure the resin is packed in the cartridge securely. The resin should be packed very tightly. When squeezed, there should be almost no flex to the cartridge.
  • The initial couple minutes of water from your RO membrane will always be high, this is commonly referred to as TDS creep. Diverting the first few minutes of water down the drain can often greatly reduce DI resin consumption. Enquire about our membrane flush systems that divert the flow restrictor.
  • Maintain low levels of carbon dioxide in your water supply.  Excess carbon dioxide will deplete DI resin quickly. If you are depleting resin quickly and have already :addressed the two options above, excess carbon dioxide is the likely culprit. You have two choices:
    • Collect the water coming from your RO system in a large container, add a powerhead or air stone and allow the CO2 to gas off. Then pump the water though your DI resin.
    • Install a CO2 removal cartridge.



Additional information

Weight 0.8 kg
Dimensions 10 × 15 × 5 cm

570 GRAMS, 3.75 KG(5 LITRES)


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