DI Vs. RO Water Specifications

The abbreviation RO stands for reverse osmosis while the abbreviation DI stands for de-ionization. Both RO and DI are techniques used to purify or remove impurities from tap and well water for use in aquariums. The RO process cannot remove all ions from water so the treatment is usually followed by DI to ensure complete removal. This combination is referred to as RO/DI.

  1. Reverse Osmosis Purification

    • When water is purified through the reverse osmosis, it is filtered through a fine, semi-permeable membrane at high pressure. This membrane is so fine that it only allows essential water molecules to pass through it. This system produces three times the waste than water that is passed through a simple purification process. The water that is being purified through reverse osmosis should have a very low silt or solid content in order to keep the membrane from clogging.

    De-ionization Purification

    • When water is purified through de-ionization, it is subjected to ion exchange resins. These resins replace the ions in the water, such as iron, magnesium and copper, with hydrogen. Nitrate, sulphate and phosphate ions are exchanged for hydroxide. The de-ionization purification process can be used by itself as it produces better quality water than water processed through reverse osmosis or in conjunction with a reverse osmosis system for improved quality.

    Indications for Use

    • Marine species cannot live in water with the typical elements and chemicals found in tap and well water. These additives can include chlorine, chloramines, nitrates, phosphates and trace metals. These compounds may cause an increase in algae growth or lead to the premature death of your aquarium inhabitants. Distilled water is available at many pet stores, fish supply stores or aquarium supply companies, but the quality of this water will differ depending on the capacity of the processor's filter and its filter replacement schedule.

    Personal De-ionization and Reverse Osmosis Systems

    • A reverse osmosis or de-ionization system can be purchased for $100 to $300, depending on the supplier. Units with a clear acrylic sump will allow you to visually inspect the system to determine when parts need to be changed. The filter size will depend on the unit's size, and filters are generally unique to the system so they may only be available from the original vendor.