In the previous articles of Chasing Color, Not Numbers we discussed the importance of Lighting, Water Flow, and Nutrition in relation to coral health and coloration. In this final article we’ll explain the 4th pillar of reef keeping, the role of filtration in reef aquariums and how it affects your reef tank and especially your corals.

You’re probably familiar with the three main filtration categories: Mechanical, Chemical and Biological, but for this article we’re taking a different approach and focusing strictly on removing organics from the water; Why it matters and how to do it correctly.

reef keeping filtration equipment and media, the 4th pillar

Organic Accumulation

Did you know your filtration system may be making your water quality worse? Imagine taking your protein skimmer’s collection cup, filled with stinking skimmate, and pouring it back into your aquarium. Sounds crazy, right? But that's pretty much what happens when you don’t operate and service your filtration system properly. Here’s why. Reef aquariums are amazing because they allow us to keep corals and other marine life alive in captivity. Technology has really advanced the hobby and made reef-keeping easier, but no matter how beautiful a tank looks, it’s got one thing working against it; the accumulation of organics.

Shallow Reef
Natural shallow reef - Tahiti. Photo courtesy of staff member, John S.

Unlike a natural reef with billions of gallons of water flushing away organic waste, our reef tanks are closed ecosystems. This means over time, organics accumulate in our aquariums. Multiple studies demonstrate that organic build-up coincides with lower disease resistance, proliferation of disease-causing organisms, reduced light penetration and an overall decline in health of aquatic life. Fortunately, we can use technology to remove these organics with the 4th pillar of reef keeping, filtration. However, filtration technology won’t help unless it’s used correctly.

Sizing Your Skimmer

skimming filtration are part of the filtration system, the 4th pillar, of reef aquariums
Red Sea Protein Skimmers rated for different organic loads.

A protein skimmer works 24-7 to strip dissolved organics out of the water. But an under-sized skimmer won’t keep up with the organic load. It’s important to size the skimmer to your aquarium based on water volume and livestock loading. As your corals grow and you feed more, the organic load increases. Never cut corners when it comes to selecting a protein skimmer. It’s important to understand that skimmers remove organics that are surface active and form foam inside the skimmer. Non-foaming organics can be removed with filtration media like activated carbon and specialty resins. More on these later.

Organic Debris Removal

Despite looking clear, your aquarium’s water is teeming with dead algae cells, crustaceans, bits of fish and coral slime and uneaten foods. The slime creates a “snowball” effect, causing the particles to clump together. This forms the sludge that builds up behind live rock and filter sumps. Filter socks are a popular and effective way of filtering out this organic debris. The suspended particles are trapped within the sock’s fibers. But if the sock is not cleaned or replaced frequently, the organic particles start to decompose and release dissolved organics and nutrients back into the water. This defeats the purpose of capturing the organic debris, because they aren’t removed from the aquarium. That’s the key to effective mechanical filtration. The particles must be removed from the aquarium, not allowed to decompose within the filter. You can avoid this by frequent cleaning filter socks, sponges and any other mechanical filtration media in your filtration system.

the auto filter roller changes out clogged filter sections, rolling in a new clean section for better filtration

Weekly rinsing or swapping of mechanical filtration media will keep it working efficiently and prevent it from becoming a source of pollution. If you’re looking for an automated solution, the AquaMaxx Fleece Filter Roller is the answer. It captures organic debris with the filter fleece and automatically rolls the dirty fleece up and out of the aquarium. The fleece roller removes the organics before they can re-contaminate your water.

Chemical Media Traps Organics

Activated carbon is an effective filter media for removing dissolved organics. It’s a time-proven technology used around the word to purify water. Synthetic resins also remove dissolved organics, but they don’t last forever, especially in an aquarium. The surface of the carbon and resin becomes colonized by a variety of microbes. Eventually the adsorption sites are filled with organics and covered by bacteria colonies. The media now acts more like a mechanical filter, trapping organic debris. These organics eventually decompose, releasing organics and algae-promoting nutrients back into the aquarium water. We recommend changing activated carbon and resins every month to prevent it from clogging with debris.

gfo, carbon, and resin can all become trapped with debris and should be changed out often

Media reactors make it easy to use granular filtration media, however GFO and nitrate removers can trap debris within the reactor too. Luckily reactors can easily be removed from the aquarium filtration system, and taken to the sink for cleaning and media change-outs. Reactors also allow you to see if the media is getting dirty.

Final Thoughts

The take-away is organics have to be removed from the aquarium, not permitted to decompose inside filter media. If not, particulate and dissolved organics will suppress water quality, which has a direct affect on your coral’s health and ability to color-up. Clean aquarium water is the 4th Pillar of Reef Keeping. You can have the latest filtration gear but unless it’s used correctly you won’t get the full benefit. Your water quality will suffer and your corals won’t grow and develop their full color potential.

We hope you enjoyed this four-part series on Chasing Colors, Not Numbers. Understanding the factors that have the greatest effect on your tank’s health and stability will do more to stimulate healthy, vibrant corals than chasing and stressing over water chemistry parameters. We’ve seen these principles help thousands of reef aquarists and we know they work for you too!