Coral need flow. SPS need a lot of flow. The wave maker (also called a powerhead, circulation pump, or gyre pump) supplies in-tank flow above and beyond the return pump. Insufficient flow means dead spots, detritus accumulation, and SPS that brown out from suboptimal nutrient delivery. Too much flow blasts coral tissue off skeletons.
Target turnover: 20-40x display volume per hour for SPS reefs, 10-20x for mixed reef, 5-15x for FOWLR.
100 gallon SPS reef = 2,000-4,000 GPH total in-tank flow. Subtract return pump GPH (typically 600-1,200 in-tank after head loss), then size wave makers to fill the gap. Two MP40s on a 100g produce ~3,000-4,500 GPH variable flow.
Propeller pumps (Vortech MP series, Tunze NanoStream): point-to-point flow, best for tall tanks, narrow flow cone. Gyre pumps (Maxspect Gyre, IceCap Gyre): wide horizontal flow, best for shallow lagoon-style tanks and large rimless reefs. Most reefers run gyres on the back wall + a single propeller for a chaotic-flow effect.
EcoTech Vortech MP10/MP40/MP60 ($300-650): the reef standard, magnetic mount (no in-tank cable), wireless control, 7+ year service life. Maxspect Gyre XF330/350/380 ($200-400): excellent gyre flow, lower cost than Vortech. Tunze Turbelle nanostream ($150-300): bulletproof German pumps. Avoid: AI Nero, Hydor Koralia (drift, fail at 18 months).
A controller-driven pump (MP40 with EcoTech driver, Gyre with cloud module) lets you program day/night flow patterns, reef-crest mode, anti-sync pulses between pumps. Static-flow pumps create fixed dead zones. Variable-flow pumps eliminate them.
High-back-corner mounting points across the rear glass produce the cleanest flow - water moves rear-to-front and gets churned by the return pump pushing back. Avoid mounting on the front glass (visual clutter, blasts coral on sand bed) or the side (creates a single circular flow loop with a dead center).
Pull pumps every 3-6 months, vinegar-bath the wet side to dissolve calcium buildup, inspect impeller and bushing wear. Replace wet-side parts every 2-3 years. Calcium buildup on impellers is the #1 cause of pump failure.