Acropora valida

Acropora valida builds rounded bushes of dense, short to medium-length branches rising from a common base. Its branches are thicker than those of Acropora tortuosa and longer than those of A. millepora; the radial corallites are tubular. In the wild it is mostly brown and cream, but in the hobby purple, pink and green forms stand out.

Because it grows fast under the right conditions and has a relatively wide tolerance range, some vendors promote it as an "easy Acropora". Still, like all Acropora it needs a mature aquarium, strong light and stable KH; that is why its difficulty is marked as "difficult".

Trade in stony corals is subject to CITES Appendix II. All the known color forms are available as aquacultured frags; buy these instead of a wild-collected colony.

• Tricolor Valida: A mostly purple body with green polyps.
• Purple Bonsai: Bright green polyps on a deep purple base.

It is one of the most widely distributed Acropora in the Indo-Pacific; it is found on reef slopes, in lagoons and on reef flats from the Red Sea to the Central Pacific. Its ability to adapt to different depths and light conditions is also the source of its tolerance in the aquarium.

• Light: High light; roughly 250–400 PAR. Purple and pink tones become more pronounced under strong light. A new frag is kept under lower light for one to two weeks and moved up gradually.
• Flow: Strong, random flow; circulation of 30–50 times the tank volume per hour is a good start.
• Placement: The upper part of the rockwork. Because it grows fast, leave 10–15 cm between it and the surrounding corals.
• Water parameters: Salinity 1.025–1.026, temperature 25–26.5°C. KH 7–9 dKH with daily swings below 0.5 dKH; calcium 400–450 mg/L; magnesium 1300–1400 mg/L. Nitrate 2–10 mg/L, phosphate 0.02–0.08 mg/L. A fast-growing colony consumes calcium and KH noticeably; adjust dosing by testing.

It is photosynthetic; most of its energy comes from the zooxanthellae algae in its tissue. Very fine powdered food given once or twice a week can support growth. Nutrients bottoming out at zero fade the purple and pink tones.

It is not an aggressive coral. Its fast-growing branches can shade neighboring corals, while it is itself vulnerable to the sweeper tentacles of LPS and the chemicals of soft corals.

Dwarf angelfish may pick at the polyps. Acropora-eating flatworms (AEFW) and red bugs are the main pests; put every newly arrived piece through a coral dip. Acropora crabs (Tetralia) are harmless.

Thanks to its fast growth it is easy to propagate. Branch tips of 2–3 cm are cut and attached to a frag plug with gel glue. Regularly pruning the mother colony also prevents the inner branches from being shaded and losing tissue.

• Rapid tissue necrosis (RTN): Occurs after sudden changes in KH, temperature or salinity. Immediately cut off and save the healthy part.
• Slow tissue necrosis (STN): Weak flow, depleted nutrients and a shaded base are the main causes.
• AEFW and red bugs: If you see bite marks, brown egg clusters or tiny dots scurrying over the tissue, dip the colony; red bug treatment also kills shrimp and crabs, so it is applied in a separate tank.
• Color loss: Browning points to a lack of light or high nitrate and phosphate.