Reef Aquarium Filtration Guide
The Foundation of a Healthy Reef Aquarium

skimmer-2_d8a12263-b740-409d-8e47-0c07f7520d2c
Proper filtration is one of the most important components of a successful reef aquarium. Effective filtration removes waste before it can degrade water quality, helping maintain stable conditions for corals, fish, and invertebrates.

While there are many filtration methods available, the best systems are often the simplest. At Pacific East Aquaculture, we have successfully maintained reef aquariums for decades using a combination of quality live rock, a shallow live sand bed, protein skimming, activated carbon, and regular water changes.

There is no single "perfect" filtration method. Every aquarium is different, and many successful reef keepers use a variety of approaches to achieve the same goal: healthy, stable water conditions that allow marine life to thrive.

Protein Skimmers: The Most Important Filtration Tool
Protein skimmers, also known as foam fractionators, are among the most effective filtration devices available for marine aquariums. By mixing saltwater with millions of tiny air bubbles, protein skimmers remove dissolved organic waste before it breaks down into nitrate and phosphate.

Why Protein Skimmers Matter
Benefits of a quality protein skimmer include:
  • Removal of dissolved organic waste
  • Improved water clarity
  • Reduced nutrient buildup
  • Increased oxygen exchange
  • Improved long-term water quality
Investing in a properly sized skimmer is one of the best upgrades a reef hobbyist can make. Choose the highest quality skimmer that fits your aquarium size and budget.

Skimmer Maintenance - To maximize performance:

  • Clean the collection cup regularly
  • Inspect air intakes for salt buildup
  • Clean pumps and impellers routinely
  • Monitor water level and skimmer output
  • Allow new skimmers adequate break-in time
A properly functioning skimmer should consistently collect dark-colored waste, commonly referred to as "skimmate."

Activated Carbon & Supplemental Filtration
Activated carbon is one of the most useful filtration media available for reef aquariums. It helps remove dissolved organic compounds, water discoloration, and various toxins naturally produced within reef systems.

For best results:
Use high-quality reef-safe carbon
Rinse media regularly
Replace monthly
Avoid relying on chemical media as a substitute for proper husbandry

Power filters and canister filters can be useful for running carbon or specialty media but are generally not recommended as the primary filtration method for modern reef aquariums.
skimmer-3

Advanced Reef Aquarium Filtration Systems
UV Sterilizers, Ozone & Reactors

As reef aquariums become larger and more heavily stocked, many hobbyists incorporate advanced filtration equipment to improve water quality and system stability. While these tools are not required for every aquarium, they can provide significant benefits when properly applied.
uv-sterilizer
UV sterilizers work by passing aquarium water through a chamber where it is exposed to ultraviolet light. The UV light helps reduce free-floating algae, bacteria, and certain parasite stages before they can reproduce within the aquarium.

Benefits of UV Sterilization
  • Improves water clarity
  • Helps control free-floating algae
  • Assists in reducing parasite populations
  • Useful on fish-only and reef aquariums
  • Commonly used on quarantine and holding systems
  • Maximizing UV Performance
For UV sterilizers to be effective:
  • Choose a unit properly sized for your aquarium
  • Keep the quartz sleeve clean
  • Replace UV bulbs as recommended
  • Maintain proper water flow rates
A UV sterilizer can be a valuable addition to many systems, but it should complement—not replace—good husbandry and quarantine practices.
ozone-system
Ozone is one of the most powerful water purification tools available to reef hobbyists. Ozone generators create ozone gas that is introduced into the aquarium system, typically through a protein skimmer, where it oxidizes dissolved organic compounds.

Benefits of Ozone
  • Crystal-clear water
  • Improved water clarity and light penetration
  • Reduction of yellowing compounds
  • Increased oxidation-reduction potential (ORP)
  • Enhanced overall water quality
Most hobbyists use ozone in conjunction with an ORP controller, which automatically regulates ozone production to maintain safe and effective levels.

Is Ozone Right for Every Reef?
Not necessarily.
While ozone can be extremely beneficial in SPS-dominated reef aquariums that require pristine water conditions, some soft corals and LPS corals may prefer systems with slightly higher nutrient levels.

As with many aspects of reef keeping, balance is important.
media-reactor_7c8a3f21-90dd-4dd8-bba1-47b5e9a6b6e7
Media reactors are versatile filtration devices that force aquarium water through specialized filtration media.

Common media include:
  • Activated Carbon
  • GFO (Granular Ferric Oxide)
  • Phosphate Removers
  • Nitrate Reduction Media
By forcing water evenly through the media, reactors improve efficiency compared to placing media in a mesh bag within the sump.

Media should be rinsed regularly and replaced according to manufacturer recommendations to maintain peak performance.
calcium-reactor_3b6d5c94-4212-4428-8ed9-1604c331db52
Calcium reactors automate the replenishment of calcium, alkalinity, and magnesium consumed by stony corals and coralline algae.

Inside the reactor, carbon dioxide lowers pH and slowly dissolves calcium carbonate media. The resulting calcium-rich effluent is returned to the aquarium, helping maintain stable water chemistry.

Advantages of Calcium Reactors
  • Automated supplementation
  • Stable calcium and alkalinity levels
  • Ideal for heavily stocked SPS systems
  • Reduced manual dosing requirements
  • Long-term cost efficiency on larger aquariums

While the initial investment can be significant, calcium reactors remain one of the most effective solutions for maintaining demanding reef systems.


DrMacTips2_5735e4c9-d7e1-490c-8035-2c508fb13e53
A Note from Dr. Mac
"After more than 50 years of keeping marine aquariums and over 25 years of coral aquaculture, I've learned that successful reef keeping doesn't require every piece of equipment on the market. While UV sterilizers, ozone systems, reactors, and other advanced filtration tools can be valuable additions, they should be viewed as enhancements to a solid foundation—not replacements for it.

In my experience, quality live rock, effective protein skimming, good water movement, regular maintenance, and consistent water changes remain the cornerstones of a healthy reef aquarium. The best filtration system is the one that matches your livestock, husbandry style, and long-term goals while allowing you to maintain stability and consistency. Focus on the fundamentals first, and you'll be rewarded with a healthier, more successful reef for years to come."

— Dr. Mac Terzich
Founder, Pacific East Aquaculture