Reef tank equipment list: what you actually need

Every reef tank is built from the same nine building blocks, plus a tenth — the protein skimmer — that you add only when you move past soft corals. The tank you choose decides how many of the others you need: an all-in-one (AIO) tank hides its filtration in a rear chamber and skips the sump, overflow and separate return pump, while a sump system opens the door to a full-size skimmer, a return pump and a reactor.

Below is every category, how to size it, and a budget / mid / premium pick named from real, in-stock 2026 products (prices verified July 2026). For the math behind each rule, the System Builder turns your tank, coral type and budget into a specific parts list.

1. The tank: AIO or sump

The tank is the one purchase that constrains everything downstream, so decide the format first. An AIO is the simplest turnkey entry — filtration lives in a back chamber, and many nano reefers run one skimmerless on softies. A sump system puts your equipment in a cabinet below, giving you room for a real skimmer, a return pump and future upgrades.

AIO prices are tank/kit; Waterbox AIO figures are tank-only (cabinet extra). Reefer G3 prices include cabinet, ATO and smart sensors but not light/skimmer/return.

Sizing note: a bigger tank is more stable, not less — more water dilutes mistakes. The most common beginner regret is buying an AIO and later wanting a sump. If SPS or a big fish load is your two-year goal, start with a sump system. Use the tank volume calculator to get true system volume (display + sump) before you size anything else.

2. The light

Reef light is sized by PAR (photosynthetically active radiation) to match your coral type, not by watts or lumens. This is the ReefRig PAR Ladder: softies want 50–150 PAR, LPS 100–200, and SPS 200–400. The number of fixtures follows ceil(tank length ÷ fixture spread) — a 48-inch tank with 24-inch fixtures needs two.

PAR figures are manufacturer (Prime) or community-measured (Hydra 32HD); Radion does not publish a 24-inch PAR value, so size it by coverage and coral type.

For the full breakdown — including Kessil and NooPsyche — see best reef LED and, for the ecosystem debate, Radion vs Kessil vs AI.

3. Flow (wavemakers)

Corals live in moving water. Total flow is sized as a multiple of system volume by coral type — the ReefRig Turnover Bands: FOWLR 5–10×, softies 10–20×, LPS 20–40×, mixed 25–40×, SPS 40–60×. The return pump carries only part of it; two opposed powerheads carry the rest and beat one big pump because they create a gyre instead of a jet.

Run two opposed units, not one. IceCap 2K is a crossflow gyre; Nero and VorTech are propeller pumps. Size total flow with the flow calculator.

Get your target GPH from the flow calculator, then pick from best wavemaker.

4. Heaters ×2 and a controller

Heating is the one category where you always buy two — a single stuck heater is the fastest way to cook a tank. Give the system 3–5 watts per gallon, split across two elements each sized to carry 60–75% of the load, and put them on an external controller. Bare titanium elements have no thermostat at all and require a controller; glass heaters have a built-in thermostat but a backup controller is still cheap insurance.

Two heaters, always. Match total wattage to 3–5 W per gallon of system volume via the heater calculator.

Size the wattage with the heater wattage calculator.

5. Protein skimmer (only past softies)

A skimmer pulls dissolved organics out before they become nitrate and phosphate. Soft-coral and FOWLR tanks can run without one; the moment you keep LPS or SPS, it earns its place. The ReefRig Skimmer Method is three checks: rate it for 1.5–2× your system volume times bioload, confirm the pump body's footprint fits your sump chamber, and confirm the chamber's water depth matches the skimmer's rated operating range.

Ratings shown for heavy bioload; each is rated far higher for light stocking. Always check footprint and water depth against your sump — see the skimmer guide.

The depth check matters more than most guides admit — see best protein skimmer for the Reefer G3 riser trap.

6. Return pump (sump systems only)

The return pump moves water from the sump back to the display. Size it for about 5× net turnover at your tank's real head height, because vertical lift and elbows steal flow: count 1 ft of head per vertical foot, plus one horizontal foot per ten, plus 1 ft per 90° elbow and 0.5 ft per 45°. A DC pump is worth it if you want controller integration.

Max GPH is at zero head; you lose flow to lift and elbows. Size net turnover to your measured head height.

7. Auto top-off (ATO)

Evaporation is fresh water leaving; it drops your water level and pushes salinity up 1–3% a day if you ignore it. An ATO replaces evaporated water automatically so salinity stays put. Buy one with two independent sensors so a stuck float can't overfill the tank, and plan a reservoir of roughly 10 gallons per 100 gallons of system.

Reservoir not included on any of these. The Apex ATK integrates with an Apex controller for alerts.

8. RO/DI unit

Tap water carries chlorine, nitrate, phosphate and metals that feed algae and harm coral. An RO/DI filter strips all of it, giving you pure water to mix salt into and to top off with. If your municipality uses chloramine, you need a dual-carbon (5-stage or better) system — a basic 4-stage won't remove it.

Only the 5- and 6-stage systems remove chloramine. Check your water report before you buy.

9. Test kits and salt

You cannot manage what you cannot measure. During cycling you test ammonia, nitrite, nitrate and pH; once corals arrive you track alkalinity, calcium and magnesium. Salt is the consumable you rebuy forever — match its mixed alkalinity to your husbandry.

• Cycle kit: API Saltwater Master Kit ($35.98) plus a refractometer (~$25) for salinity.
• Foundation kit: Salifert Alk/Ca/Mg trio ($50.05) or Red Sea Reef Foundation Pro ($79.99); add a Hanna HI772 alkalinity checker ($67.49) when you dose.
• Salt: Instant Ocean ($0.45/gal) for fish-only, Reef Crystals or Fritz RPM for mixed, Red Sea Coral Pro (~12 dKH) for SPS.

Full breakdowns live in best test kits and best reef salt. Size a water change or fresh batch with the salt mix calculator and check your reading against the salinity conversion tool.

The tenth item: dosing (later, not now)

You do not need a dosing pump on day one. Water changes replace alkalinity, calcium and magnesium until your corals consume them faster than a weekly change can keep up — roughly 0.4–0.5 dKH of alkalinity per day. Below that, skip it. Soft-coral and FOWLR tanks may never need it. When you cross the threshold, the dosing calculator sizes your daily doses.

Ready to turn this list into a specific cart? The System Builder sizes all ten categories to your exact tank, coral type and budget, and links each line to a real product. For the build order — what to buy first and when to add livestock — read how to set up a reef tank.

Prices verified July 2026 against manufacturer and retailer listings (Bulk Reef Supply, CoralVue, SaltwaterAquarium.com, Red Sea, Innovative Marine). Discontinued or superseded models are excluded from picks. Re-check current pricing before purchase.