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APEX AQ-4050 Aquarium RO/DI Water Filter System - 5 Stage - Made in USA

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APEX AQ-4050 Aquarium RO/DI Water Filter System - 5 Stage - Made in USA

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Clean Refreshing Aquarium Water for Your Fish & Plants

When you choose an APEX water filter, you'll get the absolute best water filter system for your needs from a company that values your business and will go above and beyond to ensure your full satisfaction.

Built in U.S.A.

Not only can you feel good knowing that APEX Water Filters gives Americans good-paying jobs, but you can also be certain that we carefully monitor each step in the manufacturing process because we produce our filtration systems locally.

If for any reason you're not completely satisfied with an APEX Water Filter, we'll replace it or refund the purchase price--no questions asked.

Quality Guaranteed

APEX Water Filters guarantees that our systems will meet your water filtration needs.


The AQ-4050 is designed for aquarists who want the very best water for their aquarium. This “no-compromise” reverse osmosis-deionization system produces the purest water possible for aquariums. The AQ-4040 has five stages of filtration for maximum filtration efficiency. No other filtration system will strip out contaminants like the AQ-4050. The 1-micron filter cartridge protects the reverse osmosis membrane and improves water quality by removing sediment, insoluble iron and other solids that can foul the RO membrane. The 5-micron activated carbon block adds a second layer of protection by removing chlorine, chloramine and organic chemicals. The thin film composite (TFC) reverse osmosis membrane removes algae promoting phosphates and silicates along with harmful nitrates. After passing through the RO filtration unit the water flows through two mixed-bed deionization (DI) cartridges. This special blend of ion-exchange resins scavenges any traces of nitrate, ammonia, phosphate, silicate and heavy metals like copper and lead. The DI cartridges change color as they remove traces of contaminants that may slip through the RO membrane. The twin deionization cartridges add two extra layers of protection for your sensitive corals, fish and plants. The booster pump dramatically improves the efficiency of the RO filtration system, reducing wastewater and prolonging the lifespan of deionization cartridges. The automatic back-flush feature washes mineral deposits from the RO membrane, improving performance and extending the life of the TFC membrane. The automatic shut-off system can be used with RO storage tanks. The filtration system shuts off when the storage tank (optional) is full. The glycerin-filled pressure gauge indicates when the system needs maintenance. Two digital TDS meters monitor incoming water and filtered water quality. The twin TDS meters allow you to keep a close watch on your tap water quality and filtered water quality. The AQ-4050 protects your aquarium by insuring that your water quality is consistently pure and safe every day. If you’re serious about keeping a reef aquarium, fragging corals or raising sensitive fish, the AQ-4050 is the ideal water filtration system for you! The AQ-4050 includes a canister wrench and installation kit. Replacement cartridges, membranes and optional water storage tanks are available.


  • Five-stage reverse osmosis filtration system
  • 5-micron sediment pre-filter
  • 5-micron activated carbon block cartridge removes chlorine and chloramine
  • High-efficiency TFC reverse osmosis membrane removes up to 98% of water contaminants
  • Two mixed-bed deionization post filter cartridge for 99.9% ultra-pure water
  • Booster pump insures maximum filtration efficiency
  • Glycerin-filled pressure gauge to monitor filtration efficiency
  • Digital TDS meters that monitor incoming and filtered water quality
  • Automatic back-flush system keeps the TFC membrane clean and operating properly
  • Nearly 1:1 waste to water ratio uses less water
  • Makes up to 100 gallons of water per day
  • Assembled with high-quality John Guest fittings for easy cartridge replacement
  • Made and wet-tested in our US facility

Warranty * Household water pressure can cause leaks and damage the surrounding building or fixtures if not properly installed. User must check all fittings for tightness. APEX assumes no responsibility for water damage due to leaks.

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