4-Stage RO/DI System for Reef, Saltwater, and Freshwater Aquariums
The IceCap 100gpd 4-Stage RO/DI Water Filtration System gives reef and freshwater hobbyists a reliable path to 0 TDS source water without the complexity of a powered filtration unit. Using a genuine Dow Filmtec TW30-1812-100HP membrane rated at 96-98% rejection, it strips chlorine, chloramines, heavy metals, and dissolved solids from tap water before they ever reach your tank. Output is rated at 100 gallons per day at optimal conditions, making it practical for weekly water changes on mid-to-large reef systems or frequent top-off production.
The system uses durable, clear filter canisters, so the filter condition is visible without disassembly. A glycerin-filled pressure gauge lets you confirm adequate feed pressure before each use. The refillable mixed-bed DI cartridge uses color-indicating resin — no guessing when it's exhausted. Installation uses standard 10-inch canisters and ¼-inch push-connect fittings, so replacement filters are widely available, and the system fits into any standard RO/DI plumbing setup.
Key Features:
- Genuine Dow Filmtec TW30-1812-100HP membrane with a 96-98% typical rejection rate at rated conditions
- Refillable DI cartridge extends the life of your mixed-bed resin and reduces long-term consumable costs compared to sealed cartridge designs
- Color-changing DI resin provides a clear visual indicator that the resin is near exhaustion — no TDS meter required for basic monitoring
- Glycerin-filled pressure gauge allows you to confirm feed water pressure is within the 50-80 psi optimal range before and during production
- Clear filter canisters let you inspect sediment and carbon block condition without removing them from the bracket
- Auto shut-off valve stops production when the storage vessel is full; manual flush restrictor extends membrane life
- No electrical connection required — operates entirely on incoming line pressure
Ideal For:
- Reef aquariums where corals and inverts are sensitive to chloramine, heavy metals, and elevated TDS from municipal tap water
- Freshwater planted tanks that require 0 TDS source water for precise remineralization with specific mineral profiles
- Hobbyists performing 20-50 gallon weekly water changes who need consistent, high-volume RO/DI production
- Anyone on municipal tap water with seasonal chloramine treatment or variable source quality
- New reef builds that require a large initial volume of purified water in a short window
- Aquarists upgrading from a slower 50-75 gpd unit who want more output without stepping up to a higher-pressure 150-200 gpd system
Pro Tips:
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Check your feed water pressure before assuming the system is underperforming. The 100 gpd output rating assumes 65 psi feed pressure at 77°F with 250 ppm source water TDS. Many homes run 45-55 psi, especially on upper floors or at the end of a supply line. A low-pressure condition won't damage the system, but it will increase the waste-to-product ratio and noticeably reduce daily output. If your production seems slow, check the pressure at the gauge before replacing filters.
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Flush the membrane monthly even when you're not actively making water. If the system sits idle for more than a week, bacteria and biofilm can begin forming on the membrane surface. Running a 5-10 minute flush through the manual flush restrictor before collecting water is a simple habit that extends membrane life.
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Don't let your DI resin run to full exhaustion before refilling. Once the color-change resin fully shifts to amber/yellow, TDS in the product water has already begun to climb. If that water goes into your reef, you're adding the very contaminants the system is designed to remove. Check the cartridge window weekly during high-production periods and refill before the resin is completely exhausted.
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Store a spare sediment and carbon block filter on hand. These two stages protect the membrane from chlorine degradation and sediment fouling — the most common causes of premature membrane failure. Sediment and carbon blocks are inexpensive; a replacement Dow Filmtec membrane is not. Keeping spares available means you won't be tempted to run them past their service life.
100GPD System
IC-RI100
100* Gallons Per Day
16 x 6.5 x 15.5in (LxWxH)
3:1 Waste to Water Ratio
98% Rejection Rate*
Auto Shut Off Valve
Man. Flush Flow Restrictor
Installation Adapters
50-80psi Water Pressure*
1/4in RO Tubing Required
This Product
75GPD System
IC-RI75
75* Gallons Per Day
16 x 6.5 x 15.5in (LxWxH)
3:1 Waste to Water Ratio
99% Rejection Rate*
Auto Shut Off Valve
Man. Flush Flow Restrictor
Installation Adapters
50-80psi Water Pressure*
1/4in RO Tubing Required
Learn More
150GPD System
IC-RI150
150* Gallons Per Day
16 x 6.5 x 18in (LxWxH)
1.5:1 Waste to Water Ratio
99% Rejection Rate*
Auto Shut Off Valve
Man. Flush Flow Restrictor
Installation Adapters
60-80psi Water Pressure*
1/4in RO Tubing Required
Learn More
200GPD System
IC-RI200
200* Gallons Per Day
16 x 6.5 x 18in (LxWxH)
1.5:1 Waste to Water Ratio
98% Rejection Rate*
Auto Shut Off Valve
Man. Flush Flow Restrictor
Installation Adapters
65-80psi Water Pressure*
1/4in RO Tubing Required
Learn More
*Low pressure may cause the RODI system to produce excessive wastewater. Water pressure can be increased by adding a booster pump before your RO/DI system.
