1 (844) 338-5520 Call 125 W.Victoria Street, Gardena, CA 90248 Location

APEX AQ-4020 Aquarium RO Water Filter System - Compact - Made in USA

Click Thumbnail to Zoom

APEX AQ-4020 Aquarium RO Water Filter System - Compact - Made in USA

Availability: In stock


Scroll to Options


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-4020 two-stage reverse osmosis filter is an entry-level RO system suitable for smaller freshwater, marine and reef aquariums. Perfect for nano-reefs! The granular activated carbon pre-filter removes chlorine as well as organic contaminants. The thin film composite (TFC) reverse osmosis membrane removes algae promoting phosphate and nitrate and other contaminants. Your aquarium will be cleaner and require less maintenance with reverse osmosis water. The AQ-4020 is compact and easily fits in tight spaces, allowing for easy installation. The quick connect hose fitting makes it easy to hook up the filter when you need to make water, and then store the filter system when you are finished. Replacement activated carbon pre-filters and TFC reverse osmosis membranes are available.


  • Economical entry-level two-stage RO filtration system
  • Granular activated carbon pre-filter for chlorine removal
  • TFC RO membrane removes up to 98% nitrate and phosphate
  • Assembled with high-quality John Guest fittings for easy cartridge replacement
  • Made and wet-tested in our US facility
  • Includes 3/4” non-corrosive garden hose connector for easy installation-nothing else to buy!

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.

Options & Upgrades