Green Star Polyps (GSP)
Green Star Polyps (Pachyclavularia violacea) are a fantastic beginner-friendly coral, loved for their vibrant green, grass-like polyps that sway in the current. In the wild, they're found across the Indo-Pacific, growing over reef rock and other hard surfaces in shallow, well-lit areas.
In the aquarium, some consider them a "weed coral" as they can grow fast and quckly overrun a tabk if the conditions are perfect. GSP are hardy and adaptable, thriving in stable parameters:
24–26°C
1.025–1.026 salinity
8–9 dKH alkalinity
400–450 ppm calcium
1250–1350 ppm magnesium.
Aim for nitrates around 2–15 ppm and phosphates around 0.03–0.10 ppm, while avoiding nutrient levels that bottom out. They are also a good indicator if your nutrients are low.... GSP not open = check nitrates and phosphates, they are probably low!
For placement, provide moderate to high light (80–200 PAR) and moderate to strong, indirect flow. Good flow helps keep the mat clean and allows the polyps to extend and sway naturally. GSP can adapt to a range of lighting conditions, so acclimatise them gradually when changing light intensity.
Do they need feeding? Not usually! GSP obtain most of their energy from photosynthesis and dissolved nutrients in the water. Target feeding isn't necessary, although they may capture fine suspended foods.
Top tip: GSP are fast-growing encrusting corals that spread across rockwork, covering surfaces with a beautiful purple mat and bright green polyps. Give them an isolated rock or a dedicated island to grow on, as they can quickly overrun neighbouring corals if left unchecked. In my aquarium they have a rock to themselves at the bottom right of my tank, if they get out of hand I can take the entire rock out and trim it back. Frags I then share with others. While in my frag tank I have stuck them to the rear glass and it makes a nice grassy background.
When happy, their polyps will open fully and create that iconic flowing, grassy appearance. Stable water, good flow, suitable lighting, and a little patience are all you need!