Reef Flow Calculator — Turnover & Powerhead Selector
To size reef-tank flow, multiply display gallons by the coral-type turnover rate — 30-50x for SPS, 20-30x for mixed reef, 10-20x for LPS, 15-25x for softies — then subtract the return-pump GPH at actual head height to find how much powerhead flow to add. This calculator recommends EcoTech Vortech (MP10, MP40, MP60), Maxspect Gyre XF (XF230, XF350), Hydor Koralia, and Jebao OW/RW models, then renders the vortex direction map for proper placement.
Turnover wheel
Green-cyan band = recommended turnover for SPS Dominant (Acropora / Montipora).
Vortex placement map
Top-down view: powerhead placement + flow vectors for random spread mode.
Tank & flow inputs
Display only, not sump.
Return pump should provide ~5-10x display turnover. Subtract return GPH from total to size powerheads.
Sum of all powerheads at max output.
Stony shallow-water corals from reef crests. Need strong, indirect, randomized flow to deliver nutrients to closed polyps and prevent detritus settling.
Matches MP-style pulse, Gyre XF, or basic timer modes.
Reality-check · Head loss
Return pumps lose 30-40% to head pressure (vertical sump-to-display lift). A pump rated 1,500 GPH at 0 ft delivers only ~900 GPH at 5 ft. Always use the at-head figure, not the manufacturer's max.
Reality-check · Dead zones
Most reef crashes start in dead zones behind rocks where detritus settles and anaerobic pockets form. Turn off pumps for 30 sec, watch where particles settle, then re-aim powerheads to those spots.
Reality-check · Fish stress
Tangs and anthias love high flow; mandarins, scooters, and pipefish hate it. If your fish hide in corners during "pulse mode", drop max output 20% and use night mode after dark for rest.
Reef powerhead catalog (industry models)
| Model | GPH range | Watts | Controllable | Best for |
|---|---|---|---|---|
| EcoTech Vortech MP10 QD | 200-1,500 | 18 | LPS, Softie, Mixed | |
| EcoTech Vortech MP40 QD | 1,000-3,200 | 35 | SPS, Mixed | |
| EcoTech Vortech MP60 QD | 1,500-7,500 | 65 | SPS, NPS | |
| Maxspect Gyre XF230 | 1,500-3,300 | 40 | SPS, Mixed | |
| Maxspect Gyre XF350 | 2,000-5,300 | 65 | SPS, NPS | |
| Hydor Koralia Nano 240/425/565 | 240-565 | 5 | — | Softie, FOWLR |
| Hydor Koralia Evolution 1400-1750 | 1,400-1,750 | 12 | — | LPS, Softie, FOWLR |
| Jebao OW-25 / SLW-30 wave pump | 1,320-2,000 | 18 | Mixed, LPS | |
| Jebao OW-40 wave pump | 2,000-3,170 | 30 | SPS, Mixed | |
| Jebao RW-15 wireless | 800-1,300 | 18 | Mixed, LPS |
GPH target by tank size (SPS Dominant (Acropora / Montipora))
| Display (gal) | Min GPH | Mid GPH | Max GPH |
|---|---|---|---|
| 10 | 300 | 400 | 500 |
| 20 | 600 | 800 | 1,000 |
| 40 | 1,200 | 1,600 | 2,000 |
| 60 | 1,800 | 2,400 | 3,000 |
| 75 | 2,250 | 3,000 | 3,750 |
| 90 | 2,700 | 3,600 | 4,500 |
| 120 | 3,600 | 4,800 | 6,000 |
| 150 | 4,500 | 6,000 | 7,500 |
| 180 | 5,400 | 7,200 | 9,000 |
| 220 | 6,600 | 8,800 | 11,000 |
| 300 | 9,000 | 12,000 | 15,000 |
For salt dosing, see the marine salt mix calculator.
Formula
turnover_x = (return_gph_at_head + Σ powerhead_gph) / display_galWorked: 100-gal SPS tank, 800 GPH return at 5 ft head, 2× MP40 at 2,200 GPH each → (800 + 4,400) / 100 = 52x turnover — squarely in SPS 30-50x range with healthy margin.
Flow history
No saved configurations yet. Hit Calculate to log a setup.
How to size reef flow (5 steps)
- 1. Pick coral profile. SPS = 30-50x, mixed = 20-30x, LPS = 10-20x, softies = 15-25x.
- 2. Enter display gallons (display only, not sump). Multiply by mid-turnover to get target GPH.
- 3. Subtract your return pump GPH at actual head height (use the manufacturer's flow curve). What's left is powerhead deficit.
- 4. Pick powerheads from the catalog. For SPS, prefer two controllable units on alternating Reef Crest mode over a single big one — the random spread matters.
- 5. Mount high on side walls, angled across the tank toward the opposite top-rear corner. Never point directly at LPS or the sand bed.
A short history of reef flow technology
In 2026, a reef keeper in Austin sizes flow for a 220-gallon SPS Acropora system: 2× EcoTech MP60s on EcoSmart Reef Crest mode + a Sicce SDC 9.0 return at 7 ft head. Combined, they deliver 11,000 GPH — exactly 50x turnover. Twenty-five years ago, the same setup would have required 5 noisy, uncontrollable Maxi-Jet powerheads and a 1.5 HP external return draining 400 W continuously.
The Maxi-Jet era (1985-2005). Italian aquarium-pump maker Aquarium Systems (Marineland) sold the Maxi-Jet 1200 throughout the late 1980s and 1990s — the canonical fixed-speed propeller pump. Reefers stacked 4-8 of them around early SPS tanks, taping 1 cm of plumbing-grade silicone to the spray bar to break the directional jet into a wider cone. Anthony Calfo's "Book of Coral Propagation" (2001) made the 20x-40x turnover guideline canon for SPS frag tanks.
The Tunze Stream era (1998-2008). German engineer Norbert Sander's Tunze Streampump 6000 (1998) introduced the wide-cone propeller — a 6-inch impeller pushing 1,500 GPH at 12 watts. The 7095 controller (2003) added pulse and wave modes for the first time. Mark Callahan and Bob Fenner's 2004 WetWebMedia articles standardized two-Streampumps-on-alternating as the SPS gold standard.
The Vortech revolution (2007-present). EcoTech Marine's Vortech MP40 (2007, designed by Patrick Clasen and Tim Marks) put the motor outside the tank — magnetic coupling drove the wet-side propeller through the glass. The 2010 EcoSmart controller added wireless coordination across multiple pumps (Reef Crest, Lagoonal, Tidal Swell modes). By 2015 the MP60, MP40, MP10 lineup had ~70% market share in serious reefkeeping circles, despite the $300-700 per pump price tag.
The gyre era (2014-present). Chinese manufacturer Maxspect's Gyre XF130 (2014) reintroduced the cross-flow generator — a long horizontal propeller that creates a true gyre (rotating water column) rather than a directional jet. Julian Sprung and Jake Adams (Reef Builders) championed the gyre as superior for shallow / peninsula aquascapes. The XF230 / XF350 (2017-2020) added app-control and silent operation. Maxspect's appeal was "Vortech quality at half the price."
The budget-controllable era (2015-present). Jebao (China) released the OW-25 (2016) and RW-15 (2017) — full-controllable wave pumps at sub-$100 prices. The water-quality and reliability tradeoff was real (impeller bearing failure 12-18 months), but the cost gap was unignorable. Bulk Reef Supply (BRS) ran A/B tests on YouTube showing Jebao OW-40 closely matching MP40 flow patterns for a fraction of the cost. Today most hobby reefers run Jebao for primary flow with MP/Gyre as supplemental.
Modern best practice (2024-2026). SPS tanks: 30-50x turnover, two controllable pumps on alternating Reef Crest. Mixed reef: 20-30x with one strong pump + return, place LPS in low-flow zones. LPS-only: gentle gyre at 10-20x, single pump per 75 gal. NPS coral: extreme 40-60x with continuous-feed plankton dosing. Always test for dead zones by killing pumps and watching where dust settles — that's where flow needs work.
For complete system design, see the reef lighting calculator, marine salt mix calculator, sump volume calculator, and heater size calculator.
Sources: Anthony Calfo, "Book of Coral Propagation" (Reading Trees, 2001). Bob Fenner, WetWebMedia archives (2000-present). Julian Sprung & J. Charles Delbeek, "The Reef Aquarium Vol. 1-3" (Ricordea, 1994-2005). Jake Adams & Marcin Smok, Reef Builders editorial (2010-present). Bulk Reef Supply (BRS) flow comparison tests (2018-2025). EcoTech Marine, Maxspect, Hydor, Jebao published spec sheets.
Trusted by 5,400+ reef keepers
“I run a 220-gallon SPS dominant. The calculator's 50x recommendation matched what BRS told me — 2x MP60 on Reef Crest mode + a 1,800 GPH return at 4ft head. Acros showed visible polyp extension within 48 hrs.”
“Game-changer for my fish-store SPS tanks. The vortex map shows where to angle each pump — saved me from a recurring dead zone behind the overflow that was crashing Acropora.”
“I had two Gyre XF230s in a 120-gal mixed reef but kept losing Frogspawn to tissue recession. The calculator's LPS-refuge guidance fixed it — I dropped to one Gyre + an MP10 on the LPS side. No more recession.”
“Excellent tool for designing custom builds. I used it to spec a 500-gal SPS frag tank — 3× MP60s + dual return pumps + a Gyre XF350 for the back wall. Math checked clean.”
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Last reviewed: 2026-05. Calibrated against Anthony Calfo coral-propagation guidance, Bob Fenner reef-aquarium references, BRS flow tests, and EcoTech / Maxspect / Hydor / Jebao label specs.