SYSTEM BUILDER · SALTWATER REEFS

Build a reef
that works.

Answer five questions about your tank. Get a complete, compatible equipment list — from skimmer to salt — with every spec checked against your build.

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GUIDES LIVE IN DAYLIGHT.
THE BUILDER WORKS AT DEPTH ↓

8 COMPATIBILITY RULES
EVERY SPEC CHECKED · EVERY PICK EXPLAINED

Guides

GUIDE · GETTING STARTED

Reef tank equipment list: what you actually need

A first reef needs nine things — tank, light, flow, heaters, ATO, RO/DI, tests and salt. A skimmer joins only once you go past soft corals. The full list, with sizing rules.

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COMPARISON · PROTEIN SKIMMERS

Best protein skimmer for your reef tank (by size)

Size to 1.5–2× system volume × bioload, then check the footprint and rated water depth actually fit your sump — including the Reefer G3 depth trap.

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COMPARISON · REEF LIGHTING

Best reef LED by coral type

Match PAR to coral: softies 50–150, LPS 100–200, SPS 200–400 — and how many fixtures your tank length actually needs.

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SAMPLE BUILD · FIRST REEF TANK

This is the shape of the answer.

The Builder returns a full system: every line item checked against your tank and budget, every pick explained, one honest total. The build below is a real one — a complete 40-gallon all-in-one soft-coral first reef, sized by the rule engine from catalog data verified 2026-07-03 and totaling $2,602.34. Read the full write-up, or start your own below.

TANK40 GAL · 35.4″TYPESOFT CORALFILTERAIO · NO SUMPBUDGET$2,600EXPERIENCEFIRST REEFEDIT ANSWERS ✎
SAMPLE SYSTEM · 40G AIO SOFT CORAL
TANKInnovative Marine NUVO Fusion Pro 2 40L (Long)40 gal · 35.4×19.7×13″ · all-in-one$1,550.00
CONTROLInkbird ITC-306Atemperature controller · monitors temp · 2 switched outlets$47.99
LIGHTAquaIllumination Prime 16HD Reef59W · ~100 PAR @ 24″ · 24×24″ spread$264.99
FLOWAquaIllumination Nero 3up to 2000 GPH · propeller · 2.5-60 gal$150.00
HEATEheim Jager TruTemp 150W (3616)150W · glass · built-in controller$28.01
ATOXP Aqua Duetto 2dual-sensor auto top-off · 8.2 ft lift$134.39
RO/DIBulk Reef Supply 4 Stage Value 75GPD RO/DI System75 GPD · 4-stage$143.99
SALINITYgeneric Analog Salinity Refractometer (0-100 ppt / SG 1.000-1.070, ATC)refractometer · salinity (with ATC)$25.00
TEST KITAPI Saltwater Master Test Kitammonia/nitrite/nitrate/ph · titration$35.98
SALTInstant Ocean Sea Salt160 gal box · ~8 dKH$71.99
ROCK+SANDLive rock, sand & filter mediaAIO up to ~50 gal: ~40–50 lb dry rock, a bag of sand, and rear-chamber media.$150.00
COMPATIBILITY · 8 RULES
A 40 gal all-in-one anchors the build — every other component is sized off the ~40 gal display volume you entered.
Published PAR ~100 at 24″ lands inside the 50–150 band softie corals want. 1 fixture(s) cover the 35.4″ length at ~36″ effective spread each.
softie wants 10–20× turnover (400–800 GPH). 1 pump(s) — 1× Nero 3 — deliver up to 2000 GPH combined, run throttled for random turbulence rather than a laminar jet.
R4 requires external heater control: this runs the heater on a switched, dual-probe alarmed outlet so a stuck thermostat can't cook the tank.
34 gal needs 102–170 W of heat — a single 150 W element. It runs through the ITC-306A; a mechanical thermostat is the classic tank killer.
Evaporation swings salinity on a reef; this dual-sensor ATO tops off automatically with 8.2 ft of lift and anti-overfill backup, sized for a ~40 gal system.
Tap water poisons a reef with phosphate, chlorine and metals. This 4-stage 75 GPD unit makes your top-off and mixing water (for chloramine city water, step up to a 5/6-stage).
Through the nitrogen cycle you're watching ammonia and nitrite fall to zero before adding livestock — this liquid kit covers ammonia/nitrite/nitrate/pH.
$2,602.34 / $2,600 budgetStart your build →