How to size an aquarium battery backup (filter + air + heater)

Last updated September 25, 2026. Not a lab test. Hours below are arithmetic: published watt-hours ÷ named device watts. We did not keep fish alive on a station. This is not veterinary or livestock advice.

Size backup power from two published numbers: each load’s named watts (maker page or label), and the battery or portable power station’s watt-hours.

Hours ≈ battery Wh ÷ load watts.

Aquarium outages are a stack problem. Air alone is tiny. A canister or hang-on-back (HOB) filter adds a continuous pump. A glass heater at nameplate is often ten times the filter. Tier the stack honestly: air-only → air + filter → air + filter + heater. Any thermostat off-time is unearned headroom—size from the nameplate ceiling first.

AC stations add inverter loss, so real AC hours are shorter than the raw divide. Prefer your label when it differs from a catalog row.

Affiliate note: Off Grid Power Boom may earn a commission from qualifying purchases. The site header already carries the disclosure—this is the one body reminder for this draft.

Named watts (manufacturer sources)

Air pumps — Aquarium Co-Op

Aquarium Co-Op’s Air Pump with Battery Backup page lists:

The same page states the built-in Li-ion pack can run about 20 hours continuous or about 40 hours in Power Save (15 s on / 15 s off)—Aquarium Co-Op’s claim, not a Boom runtime test. The USB-C wall path is still a ~1–2 W continuous load if you feed the pump from a power station’s USB or AC USB adapter instead of the internal pack.

Canister / external filters — Fluval 07 & Eheim classic

Fluval’s 07 series canister filter manual PDF lists WATTAGE – 120V/60Hz as:

Product landing for the mid size: Fluval 207 canister (specs match the 07 manual’s 10 W row).

EHEIM classic 250 (model line commonly called 2213) lists Power at 50 Hz of: 8 Watt.

Heaters — Eheim thermocontrol & Fluval E series

EHEIM thermocontrol 100 lists Performance at 50 Hz: 100 Watt. The thermocontrol line is sold in discrete sizes 25 / 50 / 75 / 100 / 125 / 150 / 200 / 250 / 300 W on the same product family pages.

Fluval’s US E-series product titles name the wattage directly:

Heaters cycle. While the element is on, draw is near nameplate. Average Wh over a cold night depends on room loss and set point—do not invent a duty cycle. Size as if the heater can sit on; treat thermostat off-time as bonus.

Tiered load examples (Wh ÷ W only)

Stations already used on Boom’s CPAP / nebulizer shortlists:

• Jackery Explorer 300 Plus — 288 Wh, 300 W AC
• BLUETTI AC70 — 768 Wh, 1,000 W AC

Hours = Wh ÷ stacked named watts. Not a tank test. Inverter loss ignored in the raw divide.

Tier 1 — Air only

Air-only is easy on paper. Many keepers already cover this with Aquarium Co-Op’s built-in pack (maker ~20 / ~40 h claims above)—a portable power station is optional for air alone unless you are USB-feeding several pumps.

Tier 2 — Air + filter (no heater)

Filter + air is the realistic “keep biofiltration and gas exchange moving” stack for many freshwater tanks. A mid-size station clears a day of that stack on paper; read your own canister watts if you run a 307/407-class pump.

Tier 3 — Air + filter + heater (heater assumed ON)

Read that honestly: the heater owns the Wh budget. A 288 Wh pack that looked “all day” on air + filter becomes a few hours once a 100 W element is continuous. Same pattern as continuous reptile heat loads—sustained watts, not a short nebulizer treatment.

Energy needed for a target outage at continuous nameplate (before inverter loss):

• Air double 2.1 W × 24 h = 50 Wh
• Air + Fluval 207 12.1 W × 24 h = 290 Wh
• Same + 100 W heater on 12.1+100 = 112.1 W × 12 h = 1,345 Wh
• Same + 100 W × 24 h = 2,690 Wh

UPS vs portable power station

Desktop / AV UPS: Fast transfer (often under ~10 ms on line-interactive / online units). Useful so a canister motor does not sit dead through a brief blip. Consumer UPS batteries are usually sized for minutes of PC shutdown—not multi-hour filtration plus heat. Marketing often quotes VA and “minutes,” not Wh. Fine as a bridge; weak as the overnight plan unless you verify published Wh.

Portable power station (PPS): Published Wh is usually on the box. Pure-sine AC can feed the same filter and heater plugs you already use. Many units offer UPS/EPS pass-through; transfer times vary—read the maker page. Wh capacity is why a PPS usually wins for aquarium filter + heater outages lasting hours.

Practical planning (not a livestock claim): prioritize air (or Aquarium Co-Op’s internal battery path) and the filter first; treat heater runtime as a separate Wh problem. Insulation, room temperature, and stocking density matter biologically—we are not modeling fish outcomes here.

Same overnight-device math pattern as CPAP backup battery and short-session math as nebulizer backup battery—different watt figures. Compressor cycling honesty on 12V fridge / freezer runtime is the closest cousin when a heater thermostat cycles. If you ever hardwire a transfer switch for house circuits, see transfer switch safety (listed UL 1008 gear only).

Surge notes (heater / pump / compressor)

• Glass / rod heaters (resistive): Startup surge is typically modest—near steady watts. Station continuous AC rating must still clear the heater nameplate with headroom when stacked with the filter.
• Canister / HOB pump motors: Modest inductive startup compared with fridge compressors. Still leave margin above running watts; do not size a station to run at 100% of its continuous rating.
• Chillers / air-cooled compressors: Different class—locked-rotor amps can dwarf running watts. This page does not size chillers. If you run one, get the maker’s LRA / starting current before picking a station.

Soft station shortlist (makers’ Wh; Awin / maker links)

Confirm live maker stock before you buy. Soft Awin / maker links only—no Amazon shortcodes on this page.

Jackery Explorer 300 Plus — 288 Wh

Jackery US: 288 Wh, 300 W AC. Arithmetic at ACO double 2.1 W: 137.1 hours. At air + Fluval 207 12.1 W: 23.8 hours. At that stack + 100 W heater on (112.1 W): 2.6 hours. Strong for air/filter; short once heat is continuous.

Check Jackery Explorer 300 Plus (Jackery US)

BLUETTI AC70 — 768 Wh

BLUETTI US: 768 Wh, 1,000 W AC. Arithmetic at 2.1 W: 365.7 hours. At 12.1 W: 63.5 hours. At 112.1 W: 6.9 hours. Better multi-hour headroom when a heater is in the stack on paper. Confirm kit vs bare station on the maker listing before you buy.

Check price at BLUETTI (Awin)

Jackery Explorer 1000 v2 — 1070 Wh (step-up)

Jackery US: 1070 Wh. At 12.1 W: about 88.4 hours. At 112.1 W: about 9.5 hours. Useful if the same station also covers phones, a CPAP, or a second tank—still arithmetic, not a shared-load test.

Check Jackery Explorer 1000 v2 (Awin)

Need more Wh for a 150–200 W heater through a long cold outage? Step up the station class and re-run Wh ÷ W with the maker’s published capacity—do not invent Wh. See also Boom’s portable power stations hub.

Related Boom job pages

• How to size a CPAP backup battery
• How to size a battery for a nebulizer compressor
• How to size a battery backup for reptile heat mats and heat lamps
• How to size a battery backup for an egg incubator outage
• How to size a battery for a 12V fridge
• Transfer switch safety
• How to size a power station for a mobility scooter or power chair charger
• How to size a power station for an AC chest freezer

Guides hub: how-to.

What this page does not claim

• No “kept my fish / coral alive” stories or Boom outage tests
• No invented watts—only named catalog / manual figures above
• No aquarium husbandry advice; ask a qualified aquatic vet or experienced keeper for species oxygen and temperature targets
• Heater thermostat cycling is not modeled as a fake duty cycle

Cited numbers (quick table)