Granular Activated Carbon 15 oz and 3.5 lb — Chemical Filtration for Reef Aquariums - ESV

ESV Granular Activated Carbon is a bituminous-based carbon built for chemical filtration in reef and saltwater aquariums. Its job: pulling dissolved organics out of the water column — the compounds that slowly tint your water yellow — so the tank stays crisp under your lights. It comes in two sizes, 15 oz (425 g) and 3.5 lb (1.6 kg), and ships loose, so plan on a media bag or a reactor to hold it.

Key benefits

• No phosphate leaching — the manufacturer's test results indicate this carbon releases no phosphate into your water.
• High hardness — hard granules don't crumble, so you avoid the fine carbon dust that softer grades can shed into the tank.
• Drinking-water standards — it meets the requirements of the American Water Works Association and the Food Chemical Codex, benchmarks from the potable-water and food industries you almost never see quoted for aquarium carbon.
• Generous granule size — water moves freely through the media, and mechanical straining of planktonic food organisms is reduced.

How to use it in a reef tank

This carbon ships loose, with no bag included. Load the amount you need into a Seapora filter media bag (the 12 x 8 in size suits the 3.5 lb box) and set it in a good-flow section of your sump — or run it in a fluidized reactor such as the Aquaforest AF110 media reactor for the best water-to-media contact.

ESV does not publish a dosage or a replacement schedule for this product. If you see a "grams per gallon" figure somewhere else, it did not come from the manufacturer. Email us with your tank volume and filtration setup and we'll size it with you — and see our advice below.

Technical specifications

• Base material: bituminous coal
• ESV's engineered balance between pore and granule size, active surface, ash content and hardness
• Manufacturer testing: no phosphate leaching
• Meets American Water Works Association (AWWA) and Food Chemical Codex requirements
• Manufacturer line-up: 15 oz (425 g), 3.5 lb (1.6 kg), 20 lb (9.1 kg) and a 65 lb (29.5 kg) bulk box

Available sizes

• 15 oz (425 g) — UPC 898636002464
• 3.5 lb (1.6 kg) — better cost per gram, UPC 898636002471

Why buy from ReefSolution

In business since 1999, with over 118,000 orders processed since 2010. Visit us in Laval, QC to size your filtration in person, or get it shipped anywhere in Canada.

To round out your chemical filtration stage:

• Seachem Purigen — a regenerable resin that targets nitrogenous organics; it works alongside carbon, not instead of it.
• Seachem PhosGuard — the phosphate and silicate stage of the same filtration chain.

Our advice

With any carbon, start with the rinse: run it under water until it comes out clear before it goes anywhere near your system. Use the right amount, no more. And don't leave it sitting in the tank for months — by then it has already let go of what it trapped. Carbon that stays in too long also turns into a biological filter: bacteria settle into it instead of living where they should in your system, and when you finally pull it after two or three months, you tear out part of your nitrogen cycle in one shot. Swap it out every month at the most.

— Stéphane, Aquarium ReefSolution

Frequently asked questions

How often should you change activated carbon in a reef tank?

ESV doesn't publish a replacement schedule. Our store recommendation: every month at the most — left in longer, carbon releases what it captured.

Does activated carbon leach phosphates?

Not this one. ESV's test results indicate no phosphate leaching — a common worry among reef keepers.

Should you rinse activated carbon before using it?

Yes — rinse until the water runs clear, so the carbon dust goes down the drain instead of into your tank.

15 oz or 3.5 lb — which one should I pick?

It's the same carbon in both boxes. The 3.5 lb (1.6 kg) costs less per gram if you change your carbon every month; the 15 oz (425 g) is the smaller starting size.