Improve on Mother Nature With SpectraPure ZeroTDS
SpectraPure helps you to improve on mother nature by making pure water in the comfort of your own home. For some, this might be an overstatement, but with SpectraPure, it’s actually true! Continue reading today’s post to learn more about our zero TDS (total dissolved solids) system, and shop our online store to browse all of our aquarium filtration system options.

Zero TDS and RODI Water

Nowhere in nature will you find zero TDS water, and prior to SpectraPure’s water filtration systems, you could not find it anywhere in the reefing industry either. Charles Mitsis, founder of SpectraPure, set out to provide the purest water possible to aquarium and commercial reefing enthusiasts. As a result of his mission, SpectraPure became the first company to market water filtration systems that were capable of producing zero TDS, reverse osmosis deionized (RODI) water! RODI water is now considered a standard in the industry, but not all RODI systems are created equally. Learn how SpectraPure offers the best value and performance, and you too will become a believer!


How DI Resins Work

Deionization resins (ion exchange resins) are made of polymer beads that are 0.5-1 mm in diameter. They are either negatively charged (anions) or positively charged (cations). These resins are used in combination to remove ionic contaminants from the water. When they are in solution, organic salts naturally separate into positively charged cations and negatively charged anions. As the RO product water comes in contact with these resins, the salts in the water bind to the anions and cations. The cation resins then release Hydrogen ions (H+) in the ion exchange process and the anion resins release Hydroxide ions (OH-). These released ions then combine to form pure water (H2O).

How Long Should the Resins Last?

The removal capacities of resins are expressed as ppm-gallons (parts per million to gallons). In order to calculate how much DI water your cartridges will produce before they are exhausted, divide the ppm-gallons rating by the TDS of the RO water before it enters the DI stage. For example, if your DI cartridge is rated at 6,000 ppm-gallons and the TDS of your RO water is 6 ppm, then you should be able to process 1,000 gallons of water before your DI cartridge becomes exhausted. (6,000 ppm-gallons ÷ 6 ppm = 1,000 gallons) Note: This is only a rough estimate of the life of your DI resins as it does not take into account the presence of gases such as ammonia and CO2 which do not register as TDS, but are removed by the DI stage.

Phosphate and Silicate Dumping

It is important to understand the difference between filtration and ion exchange. As the pore sites in a carbon pre-filter get filled up, the water will basically pass through it untouched. This is very different from what happens with DI cartridges. When the DI resins no longer have Hydrogen or Hydroxide ions to exchange, they release the ions with the weakest bonds in order to bind with the ions in the water that have the strongest bonds. These weakly bonded ions include phosphates and silicates. Continuing to run water through an exhausted DI cartridge results in phosphate and silicate dumping. This can actually result in a higher TDS in the water that is exiting the DI stage than was initially in the RO product water and may create disastrous results for your reef tank!

Why SpectraPure Resins Are the Best

Our proprietary MaxCap® and SilicaBuster™ resins are the result of three decades of research and testing. There are literally thousands of different variations of ion exchange resins, all of which are configured for specific purposes. While other aquatics companies use generic resin blends in their DI cartridges, SpectraPure is the only company that custom blends resins specifically for the aquatics trade. At SpectraPure, we have been custom blending resins for laboratory, industrial, and aquatic applications for almost 30 years. SpectraPure’s resins remain at their peak removal capacity for a substantially longer amount of time and have a higher removal capacity than any of the competitors’ mixed-bed or color-indicating resins.

How Do We Know Ours Is the Best?

  Since pure water is a poor conductor of electricity, purity is best measured using resistivity, which is measured in megohms. Water is considered to be ultra pure when the resistivity is 18.2 megohms. This is represented by the vertical axis on the above chart. The horizontal axis represents the total number of gallons processed. Standard inline TDS meters will typically read 0 ppm until they reach approximately .25 megohms, at which time they will read 1 ppm. They will not indicate the efficiency of the removal capacity of the DI resins up to that point. You will notice that four of the samples reach the point of exhaustion (.25 megohms) at approximately the same point, but their paths to that point are quite different, which results in entirely different removal capacities. Points to consider when reading the chart:
  • Does the water achieve a reading at or near 18.2 megohms? As you can see in the chart, the mixed-bed resin from Competitor 1 doesn’t achieve even half of that value. It starts to drop quite radically after 40 gallons and is seriously depleted after processing just over 60 gallons of water.
  • How long does the curve stay at or near 18.2 megohms? The removal capacity of the DI resins is represented by the area under the curve. Generally speaking, the longer the curve stays at or near 18.2 megohms, the greater the removal capacity of the DI resins.
  • How sharply does the curve drop from 18.2 megohms to the point where your meter reads 1 ppm? This depicts how long your DI resins work at a reduced capacity before your meter shows that it is time to replace them. The steeper the drop on the curve, the more time your DI resins spend at their peak efficiency. By analyzing the area under the curves, we can observe the correlation between the removal capacities of the different resins. Although both of SpectraPure’s resins stay at the maximum removal capacity for the same amount of time, the color-indicating resin drops more sharply, which results in a removal capacity of .9 of our standard mixed-bed resin.
As seen in the chart, both types of SpectraPure’s resins remain at their peak removal capacity for a longer amount of time and have a higher removal capacity than any of the competitors’ mixed-bed or color-indicating resins. To learn more about the science behind SpectraPure’s innovations, be sure and subscribe to our YouTube channel, SpectraPureTV, and contact us for more information on our various products. At SpectraPure, we offer up a full spectrum of solutions for reef enthusiasts, which ensures one thing — your reef tank water will be ultra pure. We know that our aquarium filtration systems outperform and outlive similar systems from our competitors, which is why we are proud to offer the water purification solutions that you need.
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