Large Scrubber in sump day 1.

A dirty grid being cleaned after one week. 12 x 18 large model.

Algae scrubbers are used to help reduce phosphates and nitrates in marine aquariums by growing algae on lighted grids in sumps. This helps prevent algae from growing in your marine display tank. It also may allow you to reduce or stop buying GFO (granular ferric oxide), a substance that absorbs phosphate. It can also allow you to increase feedings.

Size (grid) and lighting of the grid determine how much algae you grow and amount you export (phosphates and nitrates) from your system. Bigger grids grow more. Lighting both sides of the grid grow more. Setting up the lighting properly grows more. We recommend getting the light as close to the grid as possible (face of light aiming straight at the grid), while lighting up as much grid as possible. Some sump situations don't allow direct lighting and modified lighting angles are used. This will work but growth will be generally less.

In regard to type of lighting we recommend a red & blue LED Bulb 660nm & 415nm- This seems to be the sweet spot for growing nice green algae. Other lighting will of course work.


As for flow across the grid, a rule of thumb is 30-35 gph for every inch of grid that comes out of the pipe. If you can get flow from a manifold connecting that is great, otherwise the small Maxi-jets seem to work well. Example the large 12 x 18 grid should get between 360-420 /gph.


Should you have an questions feel free to contact us via the contact page. Happy Reefing!