IceCap Granular Ferric Oxide (GFO) Filter Media

Phosphate problems can quickly turn a beautiful aquarium into a frustrating battle with nuisance algae, dull corals, and declining water quality. IceCap GFO Filter Media is a premium granular ferric oxide phosphate-removal media designed to help lower phosphate and silicate levels safely and effectively in both freshwater and saltwater aquariums.

Perfect for reef tanks, fish only systems, African cichlid aquariums, planted tanks, and other high bioload systems where nutrient control is critical.

What Is GFO?

GFO stands for Granular Ferric Oxide. It is an iron based filtration media used to absorb phosphates and silicates from aquarium water.

High phosphate levels can contribute to:

• Hair algae outbreaks
• Cyanobacteria growth
• Reduced coral coloration
• Slower coral growth
• Poor water quality
• Excess nuisance algae

GFO helps bind and remove these unwanted nutrients before they become a larger issue in your aquarium.

Why Phosphate Control Matters

Many hobbyists focus heavily on ammonia and nitrate testing but overlook phosphate.

Even when nitrate levels look acceptable, elevated phosphate can still:

• Fuel algae growth
• Reduce coral coloration
• Slow SPS growth
• Irritate sensitive corals
• Lower overall water quality

In reef aquariums, phosphate is not always “bad.” Corals and beneficial organisms still need small amounts of nutrients to survive. The goal is stable, controlled phosphate levels not stripping your aquarium completely clean.

Most reef tanks aim for:

• Soft corals/LPS: around 0.03–0.10 ppm
• SPS dominant systems: around 0.02–0.05 ppm

Removing phosphate too aggressively can stress corals, so gradual reduction is always recommended.

Why Choose IceCap GFO?

IceCap GFO is designed for efficient phosphate adsorption while remaining durable and easy to use.

Features

• High capacity phosphate removal
• Helps reduce nuisance algae
• Removes silicates that contribute to diatoms
• Suitable for freshwater and saltwater aquariums
• Works in reactors or media bags
• Durable granules resist clumping
• Ideal for reef aquariums and high-bioload systems

IceCap also offers a High Capacity version designed for longer lasting performance and increased adsorption efficiency. 

How To Use

1. Rinse the media with RO/DI water before use.
2. Place into:
   • Media reactor (recommended)
   • Media bag
   • Canister filter
3. Use gentle flow if running in a reactor. The top layer should lightly tumble.
4. Monitor phosphate levels regularly.
5. Replace media when phosphate levels begin to rise again.

Recommended Starting Dosage

• Start with approximately 1 tablespoon per 8–10 gallons of aquarium water.

If your aquarium has very high phosphate levels, begin with a smaller amount to avoid reducing nutrients too quickly.

Great For

• Reef aquariums
• SPS coral systems
• LPS coral systems
• Fish-only saltwater tanks
• Freshwater aquariums
• African cichlid tanks
• Planted aquariums
• Turtle tanks
• Pond systems
• High-bioload aquariums

What's Included?

• IceCap GFO Filter Media
• Resealable container depending on selected size

Available in multiple sizes for nano tanks, medium aquariums, and large aquarium systems.

Special Order Information

Need larger quantities for a maintenance company, fish room, or large aquarium system?

Bulk sizes may be available by special order and may ship directly from the manufacturer. Bulk shipping rates may apply depending on product weight and package size.

Why Shop With Infinity & Beyond Aquatics?

Family-owned small business in North New Jersey

Real aquarium hobby experience and support

Carefully selected products we trust and use ourselves

Fast and reliable shipping

Personalized customer service

Free shipping on qualifying orders over $100

At Infinity & Beyond Aquatics, we understand how important nutrient control is for long-term aquarium success. We carry products designed to help hobbyists maintain stable and healthy systems.

Shipping Disclaimer

Orders are typically processed within 1–3 business days. Delivery times may vary due to carrier delays, holidays, weather conditions, and product availability.

Free shipping applies to qualifying orders within eligible shipping zones. Certain oversized, heavy, or specialty items may be excluded from free shipping promotions.

Please inspect all shipments upon arrival and contact us promptly with any questions or concerns regarding your order.

Stable nutrients. Cleaner water. Less nuisance algae. Keep your aquarium looking its best with IceCap GFO Filter Media.