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RODI and It's Importance!

What is RODI?

RODI stands for Reverse Osmosis Deionized Water

This process goes past regular reverse osmosis that removes between 95-98% impurities and sends it into another filter that removes calcium, sodium, and chloride ions and replaces them with hydroxyl ions and hydrogen ions making it 100% pure. 

Most RODI filters contain 4 flters; Sediment, Carbon, RO Membrane,

and a Deionization Chamber. 

Is Distilled Water the Same as RODI?

No. They are processed differently which matters. RODI goes

through a stage of deionization that distilled doesn't.

Why Does It Matter?

When maintaining an ecosystem of living creatures, we try to eliminate any outside possibilities of chemicals, pest, disease or anything else that could potentially harm your ecosystem. Because RODI goes through an extra stage of deionization it makes it more reef safe and less harmful for your tank. There are also many water conditioners that people add to their water that may make it "safe" but won't stop buildup of contaminants and compounds. We prefer RODI water because it removes outside factors, and this will also help with narrowing down any issue if dealing with tank problems. It is also a way of not adding unknown metal or other trace elements that can be extremely harmful to your ecosystem. Tap water contains metals as well as phosphates and nitrates that could lead to algae and other nutrient issues if added to your tank. If you plan to keep sensitive fish, SPS or even most LPS corals, RODI is necessary as it eliminates outside issues that could affect the water hardness, the salinity or the nutrients. 

What is TDS?

TDS stands for Total Dissolved Solids. These solids are ions such as Calcium, Sodium, Magnesium, Phosphate, Nitrate and Silicate, which can effect the stability of our reef tanks. Many hobbyists will purchase a TDS meter for their RODI system to let them know when the quality of water is deteriorating and filters need to be replaced. 

We recommend changing filters when TDS reads above 1 ppm. 

In tap water, TDS standards are typically 250ppm - 500ppm which is why we do NOT recommend using tap water. When ppm is at 500 it is treated for high metals or toxicities like chemicals, pesticides and sewage. Even tap water going through Reverse Osmosis (RO) units can still miss ammonia and silicate that can harm some fish and inverts. 

Our Recommendations


Aquatic Life 100 GPD 4 Stage

(Top Recommendation)

  1. Easy twist in replacement cartridges

  2. Smaller and compact to fit in smaller areas

  3. Easy set up and overall use

  4. 100 gpd (gallons per day)

4-7 Stage RODI Unit

  1. Filters are the cheapest to replace in these units

  2. Will need the wrench to replace filters and ensure it's tightly on to keep from leaking

  3. 75 gpd (gallons per day)

TDS meter.jpg

TDS Meter

  1. Helps keep an eye on your RODI filter's effectiveness.

  2. Can be calibrated for accuracy.

  3. Some have multifunction allowing to test temp or connect to Wi-Fi allowing for easier monitoring.

Useful RODI Parts

rodi faucet adapter with ball valve.jpg

Faucet Adapter with ball valve

This adapter allows you to switch your water supply back to the faucet or to the RODI unit without the hassle of removing the adaptor after every use. 

Faucet Adapter

There are several faucet adapter sizes available. The most commonly used are hose adaptors and 1/4" faucet adapters. These will be what attaches the RODI tubing into your main water supply. 

Float Valve

This float valve can be used in the container you are filling and once it's full, the ball is pushed to the surface and it stops refilling, preventing the water from overflowing.  

Filter Wrench

This is necessary for many RODI units to tighten and loosen filter chambers.

When to change your RODI Filters

Sediment:                Every 6 months or if completely brown


Carbon:                   Every 6 months


RO Membrane:       Yearly


DI Resin:                 Color changing resin indicates when it                                     needs to be changed


                               If TDS is reading above 1 ppm, this is an                                   indicator that filters need to be changed. 

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