Acropora Carduus

Alkalinity: 7.5-9 dKH
Calcium: 410-440 ppm
Magnesium: 1350 ppm
Phosphate: 0.00-0.06 ppm
Nitrate: Low to Zero
Flow: Strong Turbulent
Lighting: Medium to High
Placement: High

This specific Pacman colony was kept under LED’s only.


Scientific Name: Acropora Carduus
Common Aliases: Pacman Acro – specific colouration / Bottle brush acro
Growth Pattern: Branching
Care Level: Intermediate – requires control of P04 & Alkalinity
Lighting: Mid tank with LED or Halides, Higher placement with T5’s. 
Flow: Turbulent to strong
Most Sensitive to: Alkalinity swings & Phosphate
Common Problems: Alkalinity swings causes bleaching/recession
Where to Start: Stable alkalinity and controlled, low phosphate levels


Acropora Carduus have thin, somewhat delicate branches that can be easily damaged, especially as frags. Care needs to be taken when placing this coral so as not to damage its branches. Due to it’s thin branches, it grows fairly quickly. This acropora requires strong lighting conditions and strong, turbulent flow. Ideal placement is in the top section of the tank with direct lighting. Elevated phosphate levels will effect the colouration of the pacman acro and should be kept low-to-zero prior to adding acropora to the system.

Lighting & Water Flow:

Branching acropora require high lighting conditions more than any other coral. The colouration of acropora is dependant on several factors, lighting being the most effective next to phosphate levels. This specific colony was kept under an LED only lighting system approximately 12-14″ under the light fixture. T5 lighting systems generate excellent results with the least amount of input from the reef keeper for SPS corals. Similar, if not better, results can be achieved with LED or combo lighting systems but require much more experience and input from the hobbyist.

  • Low Light = 30-50 PAR
  • Medium = 50-150 PAR
  • High Light = 150+ PAR

Strong turbulent water movement is recommended as this will produce a denser coral structure and growth pattern. Never aim a powerhead directly at a coral as this can cause tissue recession and damage. Randomizing the flow around the coral often provides the best results and will prevent detritus from settling within the colony’s branches.

Feeding & Growth:

Acropora are photosynthetic corals that rely heavily on food from the zooxanthellae algae that they host within their tissue. However, they also benefit greatly from regular feedings and will extend their polyps searching for small food particles and plankton. SPS corals generally require the smallest of food particles, <1-150 um (microns) is the recommended range.

Feeding SPS corals can increase growth rates and affect colouration. Care should be taken in systems with already high nutrient levels. Regularly feeding corals can also increase the need for water changes due to the regular addition of nitrate and phosphate sources.

Other Notes:

Overfeeding your system can lead to increased phosphate, nitrate and nutrient levels. This can in turn cause other issues. High nutrient levels and overfeeding can contribute to Vermetid Snails proliferating throughout your system. These tube like worms extend a ‘string’ that can sting acropora and other coral tissue. Ostreobium algae (green coral boring algae) can also become more active in high nitrate conditions.

Dramatic changes in nutrient and/or phosphate levels can also affect the corals ability to process skeletal building elements, affect changes in colour, growth and even contribute to STN/RTN. Various other algae issues may also arise, so care should be taken when beginning a regular feeding regiment or changing to more concentrated food sources.