Why does my RR Firecracker Acropora (Acropora tenuis) lose its red/orange pop and turn pinkish or brown under the same PAR?

Color in this tenuis is highly spectrum- and nutrient-dependent. It holds reds best under strong blue/UV (420–450 nm) with moderate w

The tips are white—am I seeing healthy growth, bleaching, or alk burn?

White axial tips with visible polyp bumps are normal growth. If the white area spreads down branches and polyps vanish after a light increase, that’s likely light shock—reduce intensity 15–25% and ramp over 2–3 weeks. If tips erode with a harsh line while nutrients are low and alkalinity >8.8 dKH, think alk burn; lower alk to 7.5–8.3 and raise nutrients gradually.

How can I prevent the base from dying off on a maturing colony?

Tenuis can self-shade. Mount the frag at a slight angle to expose the base, provide strong, random flow to keep detritus off the foot, and give 2–3 inches of clearance from neighboring corals. Periodically trim upper branches to open light paths. Avoid large colonies of aggressive LPS nearby—occasional contact stings can trigger slow tissue loss at shaded bases.

What pests specifically trouble this tenuis, and how do I confirm them?

Watch for Acropora eating flatworms (AEFW) and red bugs. AEFW leave crescent bite marks and tan dust when blasted with a baster; eggs ring the undersides of branches. Red bugs cause dull color and poor polyp extension. Quarantine new pieces, inspect under blue light with a white flashlight, and use dips for AEFW (repeated, egg-safe protocols) and milbemycin oxime in QT for red bugs.

RR Firecracker Acropora Coral

Acropora

Overview

RR Firecracker Acropora Coral shows dense, upward-branching growth with bright red to orange tips and contrasting polyps. Acropora tenuis, a branching small polyp stony coral, prefers strong lighting and high, turbulent water flow. It is photosynthetic via symbiotic algae but can benefit from occasional small planktonic foods to support growth and color. Place high on stable rockwork with space from aggressive corals, and keep alkalinity stable with low nutrients to prevent stress.

Quick Facts

Care Difficult

Lighting High

Flow High

Placement High

Temperament Peaceful (short sweepers; allow 2–3 inches for growth)

Recommended Parameters

Temp 76–80°F

pH 8.1–8.4

Salinity 1.025–1.026

Calcium 420–450 ppm

AlkAlkalinity 8–9 dKH

Magnesium 1280–1350 ppm

Feeding photosynthetic, microplankton, zooplankton, rotifers, copepod nauplii, powdered coral foods (e.g., Reef-Roids), marine snow, amino acid supplements

Care & Placement

RR Firecracker Acropora Coral (Acropora tenuis) thrives under high, stable conditions typical for SPS. Provide strong, blue-leaning light at 250–400 PAR; acclimate by starting mid-level or using screen layers, then move it higher over 2–3 weeks to avoid bleaching. Deliver high, random flow (aim for 30–50x tank turnover) using alternating pumps to keep detritus off branches and promote gas exchange. Target-feed occasionally with very fine zooplankton or amino acids at night, but prioritize clean, stable water. Keep temperature 75–78°F (24–26°C), pH 8.1–8.4, salinity 1.025–1.026 (35 ppt), calcium 420–460 ppm, alkalinity 7.5–8.5 dKH (pick a number and hold it), magnesium 1280–1380 ppm, nitrate 2–10 ppm, and phosphate 0.02–0.07 ppm. Test 2–3 times weekly when dialing in dosing (two‑part, kalkwasser, or a calcium reactor) and use an ATO to prevent swings. Place high on stable rock with strong flow exposure; leave 2–3 inches from neighbors to avoid stings and shadowing. It is peaceful but sensitive to chemical warfare from soft corals—use carbon and regular water changes. Dip and inspect for pests (AEFW, red bugs); quarantine if possible. Signs of stress include paling/bleaching (excess light or rapid nutrient drops) and tissue recession (instability or pests). Correct by restoring stability, reducing light intensity, increasing flow, and addressing pests promptly.

FAQ

Frequently Asked Questions

About the RR Firecracker Acropora Coral

Why does my RR Firecracker Acropora (Acropora tenuis) lose its red/orange pop and turn pinkish or brown under the same PAR?

Color in this tenuis is highly spectrum- and nutrient-dependent. It holds reds best under strong blue/UV (420–450 nm) with moderate w
The tips are white—am I seeing healthy growth, bleaching, or alk burn?

White axial tips with visible polyp bumps are normal growth. If the white area spreads down branches and polyps vanish after a light increase, that’s likely light shock—reduce intensity 15–25% and ramp over 2–3 weeks. If tips erode with a harsh line while nutrients are low and alkalinity >8.8 dKH, think alk burn; lower alk to 7.5–8.3 and raise nutrients gradually.
How can I prevent the base from dying off on a maturing colony?

Tenuis can self-shade. Mount the frag at a slight angle to expose the base, provide strong, random flow to keep detritus off the foot, and give 2–3 inches of clearance from neighboring corals. Periodically trim upper branches to open light paths. Avoid large colonies of aggressive LPS nearby—occasional contact stings can trigger slow tissue loss at shaded bases.
What pests specifically trouble this tenuis, and how do I confirm them?

Watch for Acropora eating flatworms (AEFW) and red bugs. AEFW leave crescent bite marks and tan dust when blasted with a baster; eggs ring the undersides of branches. Red bugs cause dull color and poor polyp extension. Quarantine new pieces, inspect under blue light with a white flashlight, and use dips for AEFW (repeated, egg-safe protocols) and milbemycin oxime in QT for red bugs.