PC Rainbow Acropora

PC Rainbow, from Pro Corals, is a rainbow-gradient acro that stacks its colors along each branch: red-pink at the base, shading through orange and green, finishing in blue-purple growth tips with bright polyps. A single frag can look unfinished — mostly green, mostly red — because the full gradient develops as the colony grows and each branch matures. Grown out, it is one of the few acros that genuinely shows four or five distinct colors at once under reef lighting.

The care card reads like the rest of the high-end acro shelf. Strong, blue-weighted light at the top of the aquascape; heavy random flow; alkalinity pinned in the 8–10 dKH range with calcium 400–450 ppm and salinity near 35 ppt. The rainbow is a high-light phenomenon: in moderate light the colony stays healthy but holds only its green and red base colors, and keepers chasing the full gradient move the piece upward in stages. Nutrients should register on a test kit — rainbow acros in zero-nutrient systems classically stall and pastel out.

Growth starts with the familiar encrusting phase, then branches rise and the color bands form along them. Because the gradient follows branch age, a colony that gets fragged constantly never shows its best face; let it grow. Fragging itself is standard — tip cuts, mounted upright, encrust first. Space it away from faster acros, since PC Rainbow grows at a moderate pace and loses territorial fights to the quick staghorns.

Field notes — what keepers report: The most repeated keeper observation is that the rainbow arrives with size — small frags disappoint, year-old colonies deliver. Keepers also report the blue tips depend on spectrum, showing strongest under LED systems with heavy blue and violet channels. A few keepers place it a notch lower than their tenuis shelf and report better polyp extension there, so there is honest disagreement about whether it wants the absolute top of the tank.

Photo: MolaAcropora (CC BY 4.0), via Wikimedia Commons. The photo shows an aquacultured Acropora frag with rainbow coloration of the type this strain develops; PC Rainbow is an aquacultured Acropora selection, chosen for the multi-color gradient described above.