Aquarium RODI Systems
Reef-grade RO/DI built to last, from membrane to fittings — TDS at or near zero.
Pick the right system in three steps.
- Test your feed water (TDS, pressure, temperature).
- Set your target output in GPD.
- Match a system rated for that output at your conditions.
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How to choose
How to choose an aquarium RO/DI system
The right system comes down to three things: your feed water (city or well, and how high its TDS runs), your target output in gallons per day, and how often you do water changes. Reef and planted tanks need water at or near 0 TDS — that final purity is what the DI stage delivers after the RO membrane.
Match output to your tank. A single tank under ~75 gallons is well served by a 90 GPD system. Larger tanks, multiple tanks, or frequent water changes are better with 150–300 GPD so you’re never waiting on the system to fill.
City water vs. well water. Chlorinated city water is fine with a standard carbon block. If your utility uses chloramine, add a catalytic carbon stage so it doesn’t foul the membrane. High-TDS or high-silica well water benefits from our MaxCap roughing and Silica Buster DI cartridges.
Not sure which to pick? Take the 2-minute Find My System quiz or read the buying guide. Already have a system and just need refills? Shop replacement filter kits.