Overview
An algae turf scrubber (ATS) grows algae on purpose — on a lit screen in a controlled spot — so that harvesting that algae exports nitrate and phosphate from your system. It is a natural, chemical-free nutrient-export method that has grown a devoted following. Here is how it works and whether it belongs on your tank.
How an Algae Scrubber Works
Nutrients that would otherwise feed nuisance algae in your display are instead consumed by algae growing on the scrubber’s screen under strong light and flow. When you scrape and discard that growth, the nitrogen and phosphorus bound up in it leave your system for good. The three ingredients are light, flow, and a rough screen for the algae to grip.
The Upside
An ATS exports nutrients naturally with no dosing or chemicals, adds oxygen and helps buffer pH, and cultures copepods and other microfauna that feed your tank. Many reefers love that it turns nutrient export into a living, self-regulating process rather than a bag of media to replace.
The Tradeoffs
Scrubbers need light and space, take a few weeks to mature before they really pull nutrients, and can leach yellowing compounds into the water — so run activated carbon alongside one. They also require periodic harvesting and a little tuning to dial in. They are effective, not effortless.
ATS vs Skimmer vs GFO vs Refugium
An algae scrubber targets nitrate and phosphate, the same job as a refugium full of macroalgae, and it complements a protein skimmer (which removes organics earlier) rather than replacing it. Compared with GFO, a scrubber exports both nitrogen and phosphorus and never needs media replacement, but it is slower and bulkier. Many systems run a scrubber plus a skimmer.
DIY vs Buy
Scrubbers are famously DIY-friendly — an LED, a pump, and a roughed-up screen will do — but commercial units are compact, quiet, and easier to size correctly. Choose based on your space and how much tinkering you enjoy.
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Frequently Asked Questions
Do I still need a skimmer if I run an algae scrubber?
Not necessarily, but they work well together. A scrubber exports nitrate and phosphate, while a skimmer removes organic waste before it breaks down. Many reefers run both for extra stability; others run a scrubber alone successfully.
How long before an algae scrubber starts working?
Usually two to four weeks. The screen has to grow in and mature before it consumes meaningful amounts of nutrients, so give it time and resist harvesting too aggressively early on.
Will an algae scrubber cause algae in my display tank?
No — done right it does the opposite. By consuming the nitrate and phosphate that fuel nuisance algae, a well-run scrubber starves algae in the display. Run carbon alongside it to handle any yellowing it releases.