Chemical Filtration
Chemical filtration refers to the use of specialized media, such as activated carbon, GFO, and various resins, to remove dissolved compounds from aquarium water that mechanical and biological filtration can’t address on their own. Where mechanical filtration physically traps debris and biological filtration relies on bacteria to process waste, chemical filtration works through adsorption, binding unwanted molecules directly to the surface of the media as water passes through.
Together, these three filtration types form a complete strategy, each targeting a different category of waste and impurity present in a reef aquarium.
Why It’s Important
- Removes dissolved organic compounds and discoloration that mechanical and biological filtration leave behind.
- Improves overall water clarity by targeting compounds responsible for yellowing or cloudiness.
- Targets specific nutrients, such as phosphate, through specialized media like GFO.
- Complements mechanical and biological filtration rather than replacing either one.
How It Works
Chemical filtration media is typically placed in a dedicated reactor or a simple filter bag positioned in an area of strong water flow. As water passes through or around the media, dissolved molecules bind to its porous surface through adsorption, gradually removing them from circulation. Different media types are formulated to target different compounds, from general organics with activated carbon to phosphate specifically with GFO.
Over time, chemical filtration media becomes saturated as available binding sites fill up, which is why it needs to be monitored and replaced on a regular schedule to stay effective.
Chemical Filtration and Related Methods
Chemical filtration works alongside mechanical filtration and biological filtration as part of a complete filtration approach, each addressing a different type of waste. It’s directly tied to activated carbon, GFO, and adsorption, the underlying mechanism that makes chemical filtration media effective in the first place.
Activated carbon is generally considered the workhorse of chemical filtration, tackling a broad range of dissolved organics, discoloration, and even some toxins, while GFO is used more specifically to target phosphate. Some reef keepers also use specialized resins for particular concerns, such as removing dissolved metals or specific medications after a treatment period. Because different media serve different purposes, many tanks run more than one type simultaneously, often in separate reactors or filter bags, rather than relying on a single chemical filtration method to address every possible water quality issue at once.
Common Misconception
A common misconception is that chemical filtration alone can substitute for biological filtration. In reality, the two address entirely different problems: chemical filtration removes dissolved compounds and toxins, while biological filtration relies on bacteria to process ammonia through the nitrogen cycle, a function chemical media simply doesn’t perform.
The Bottom Line
Chemical filtration uses specialized media to remove dissolved organics, toxins, and specific nutrients from reef aquarium water through adsorption. Used alongside mechanical and biological filtration, and replaced on a consistent schedule, it plays an important supporting role in maintaining overall water quality.
