Don't take our word for it. See exactly how it works.
We describe every process in Oquari the way it actually works: what measures and watches it (sensors), what does the work (pumps, valves, outlets), and what happens when something goes wrong (safeguards). Freshwater, planted and marine aquariums all get the same serious treatment — each feature is labeled with the tank types it's built for.
Temperature — heating and cooling
Two independent water temperature sensors watch over the tank — the controller regulates by their combined reading, and when they start to differ by more than half a degree, it treats the measurement as unreliable: heating stops and you get an alarm. The primary heater holds the target temperature with hysteresis and a day/night mode; the backup heater joins in only when the first can't keep up for half an hour — or runs as a separate zone. When things get too warm, Oquari first smoothly spins up the fans, and only then switches on the chiller — with minimum run and rest times that protect its compressor.
What measures and watches
- 2× water temperature sensor — independent, cross-checking each other
- room temperature and humidity sensor
- current metering on each heater channel — "is the heater actually heating?"
- minimum water level sensor
What does the work
- two protected heater channels (primary + backup, or two zones)
- cooling fans with smooth speed control
- a chiller outlet with compressor protection (minimum run/rest times)
Safeguards
- sensors diverging by >0.5 °C → heating STOP + alarm
- lost temperature reading → heating STOP
- emergency threshold → heater power cutoff + critical alarm
- water level too low physically locks out the heaters — even if the electronics fail
- room for a classic mechanical thermostat as the last line of defense
- a "heater can't keep up" alarm when heating takes suspiciously long
ATO top-off — replacing evaporated water
Water evaporates — the level drops — salinity and hardness rise. ATO replaces the loss with RO water from the reserve tank. The process: the working sensor must indicate a low level continuously for a set time (a momentary ripple won't start the pump); only then does the valve open and the top-off pump start. A flow meter on the line confirms water is actually moving. Top-off ends when the level returns to normal — and every cycle is logged, so you can see how much your tank evaporates each day. A sudden change in the evaporation rate is valuable information in itself: often the first sign that something's wrong.
What measures and watches
- working level sensor (top-off start/stop)
- maximum level sensor — independent of the working one
- top-off flow meter — confirms actual flow
- reserve tank level sensors (empty/full)
- leak sensors under the tank and by the reserve tank
What does the work
- top-off pump with current metering (detects dry running)
- top-off solenoid valve — normally closed
- reserve tank stirring pump — started before top-off so the water is uniform
Safeguards
- per-cycle time limit — the pump never pumps "forever"
- daily volume limit (e.g. 2% of tank volume)
- no confirmation from the flow meter → STOP + alarm (blocked hose, dry pump)
- maximum level sensor = a hard stop independent of the top-off logic
- empty reserve tank → STOP + "refill RO water" alarm
- after any limit violation, resuming requires your confirmation
Automatic water change — no more bucket and hose
The classic 20–30% weekly change means a parameter jump every single time — temperature, salinity, pH. Oquari flips that logic: instead of rare big changes, it makes frequent, very small ones. You enter one number — liters per week — and the controller splits it into small portions changed around the clock. Your livestock lives in stable parameters, and you stop hauling buckets.
How one cycle runs
- Status check: a change starts only when the water level is correct, no feeding or service is in progress, and no alarm is active.
- Drain: the drain pump and solenoid valve send a measured portion to the sewer. Volume is counted by a flow meter — to the portion, not "by eye".
- Stabilization: the system waits for the level to settle and verifies the drop matches the plan.
- Refill: the refill valve opens and fresh water replaces exactly what was removed — supervised by a second flow meter and the level sensor.
- Log: the cycle's volume, time and status go into the history. You know what happened, and when.
Freshwater and planted vs marine
In a freshwater or planted tank, fresh RO water goes directly into the aquarium — the architecture is simple, with no intermediate tank.
In a marine tank, pure RO water must never go straight in — it has to match the tank's salinity exactly. That's where the saltwater mixing reservoir comes in: the RO membrane fills it automatically, a circulation pump mixes it, a doser adds a calculated portion of concentrated brine, and a salinity probe verifies the result within the set tolerance — only then is the water marked ready for a change.
If no ready saltwater is available, the change waits. Under no circumstances will the system let pure RO reach the reef.
What measures and watches
- level sensors: minimum, working and maximum
- 2× flow meter — one for the drain, one for the refill
- salinity probe in the mixing reservoir (marine)
- RO water purity sensor (TDS)
- water temperature sensor in the reserve tank
- leak sensors under the tank and by the reservoir
What does the work
- drain pump + drain solenoid valve
- fresh-water refill solenoid valve and pump
- RO membrane fill solenoid valve
- reservoir circulation pump / stirring pump
- brine doser (marine)
- heaters and UV lamp automatically secured while the level is lowered
Overflow and flood protection
- maximum level sensor = a hard stop on refill, independent of the program
- flow meters compare the plan against reality — a deviation means a possible leak: valves and pumps cut off immediately + alarm
- double-cycle lock: the next drain won't start until the level is back where it was before the previous one — the aquarium can't be gradually drained
- level too low → everything stops; no equipment runs dry
- failed-cycle counter: after a few attempts the system stops completely and asks for intervention
- a leak sensor aborts the change in a split second and closes the valves
The reserve tank and RO water production
Top-off and water changes are only as good as the water they're given. Oquari supervises the whole chain: when the reserve tank level drops to minimum, it opens the RO membrane valve and fills it back up — in long, infrequent cycles that extend membrane life. A water purity sensor (TDS) measures the quality of the water produced: a rising reading means the membrane is wearing out — you get an alarm before substandard water flows into the tank.
What measures and watches
- reserve tank level sensors (minimum / full)
- RO water purity sensor (TDS)
- reserve water temperature sensor
- leak sensor by the tank
What does the work
- RO membrane fill solenoid valve
- a stirring pump keeping the water uniform
Safeguards
- the full-tank sensor closes the valve — filling ends
- fill time limit: no level response → STOP + alarm (broken hose, no pressure)
- purity threshold exceeded → "check the membrane" alarm
- leak by the tank → valve closed immediately
Dosing to the milliliter
Up to four dosing channels — macro and micro fertilizers in a planted tank; calcium, carbonate hardness and magnesium in a reef; care products in freshwater. You calibrate each pump once, with a simple procedure: one minute of running, measure the output, the controller does the math. It spreads the daily dose into smaller portions within your chosen time window so parameters don't jump — and keeps a set gap between different liquids, an iron rule in marine chemistry (some liquids precipitate when dosed together). Channels never dose at the same time.
What measures and watches
- motor current metering on every pump — detects air locks and an empty container
- liquid usage counter per channel
- battery-backed clock — the schedule works without the internet
What does the work
- up to 4 peristaltic pumps with volume calibration
- doses split into portions (e.g. 4× daily) within a time window
- queueing: one channel at a time, with spacing between liquids
Safeguards
- a hard daily volume limit — even a misconfiguration can't overdose
- air lock / empty container → channel STOP + alarm, resume after confirmation
- advance warning: "container empty in ~5 days"
- on power loss dosing stops; after recovery it doesn't "catch up" blindly — the daily balance is preserved
- paused during feeding and water changes
CO₂ driven by actual pH
Instead of dosing CO₂ "by feel" from a timer, Oquari drives the valve by the water's actual pH: falling pH means enough CO₂ — the valve closes; rising pH opens it again. It's all synchronized with the light schedule: dosing starts ahead of sunrise (plants get CO₂ from the first minute of photosynthesis) and ends before dusk. At night the valve stays closed.
What measures and watches
- pH probe with temperature compensation
- the light schedule as a time gate
- probe diagnostics: disconnect and drift detection
What does the work
- CO₂ solenoid valve — normally closed
- control to the target pH with hysteresis
- a probe-free timer mode (schedule), if you prefer it simple
Safeguards
- a hard lower pH limit: below it, the valve closes and raises an alarm — regardless of the control loop
- probe failure or disconnect → valve closed immediately (safe state)
- always closed at night — the light gate can't be bypassed by accident
Light like in nature
Up to four channels of smoothly dimmed lighting, each with its own daily plan built from points (up to 10 per channel) — the controller glides between them, giving natural sunrise and sunset ramps instead of "someone flipped the fluorescents at 7:00". Plus any number of lamps switched from the metered outlets. Planted tanks will appreciate the midday break (siesta); marine tanks — moonlight following the real phases and a passing storm effect. New livestock? One setting caps the whole lighting system's power for the acclimation period.
What measures and watches
- battery-backed clock — the plan works without the internet and through outages
- an astronomical calendar for the moon phases
- a room light intensity sensor (optional)
- lamp hour counters — know when they lose output
What does the work
- 4 smooth dimming channels (the control standard adopted by lamp manufacturers)
- 230 V outlets for lamps switched as a whole
- a moonlight channel
Special modes
- sunrise and sunset ramps (30/45/60 min presets)
- siesta — a midday break for planted tanks
- storm — random dimming for reef and planted tanks
- acclimation — a global power cap for new livestock
Wave pumps and circulation
A reef needs water movement — but not monotonous movement. Oquari drives up to four circulation pumps with smooth power control and wave programs: constant, sine, pulses, random waves and tidal mode — two pump groups working alternately over a multi-hour cycle, recreating the reef's daily rhythm. At night the flow automatically calms down with the light plan. Every pump starts on a gentle ramp, and its power draw is continuously metered.
What measures and watches
- real-time current metering on every pump
- the light schedule — drives night mode
- feeding mode — the pause signal
What does the work
- up to 4 pumps with smooth power control and soft start
- A/B groups in antiphase for tidal mode
- a return pump (sump setups)
Safeguards
- dry running: the pump is on but the current is suspiciously low → STOP + alarm before it burns out dry
- jammed impeller: current too high → stop, three restart attempts, then an alarm
- feeding pauses the waves at one button — and brings them back on its own
Feeding and operating modes
A physical button on the device, an app command or the auto feeder schedule — one action starts the whole choreography: wave pumps and filtration pause, dosing and water changes wait, the feeder drops a portion, and after the set time everything returns to work on its own. Then there's service mode — safe hands-on work at the tank (heaters off, level alarms deliberately muted) — and vacation mode: the feeder on a plan, economical lighting and heightened alarm vigilance while nobody's home.
What measures and watches
- a feeding button on the device (works with wet hands too)
- a lid-open sensor (optional)
- a timer — back to normal operation after the set time
What does the work
- an auto feeder (pulse with repeats)
- pausing the wave pumps, filtration and protein skimmer
- holding dosing and water changes for the duration of feeding
Safeguards
- automatic return from feeding — you can't "forget the pumps off"
- service mode ends itself after an hour of inactivity
- in vacation mode, alarms get more vigilant, not less
Water chemistry — probes that look after themselves
The probe module measures pH, redox (ORP) and conductivity in two independent circuits — from pure RO water to full marine salinity. In a planted tank, pH drives the CO₂; in marine you see salinity in PSU and specific gravity, while ORP speaks to the reef's biological condition; in freshwater, conductivity and TDS guard water quality. Calibration is run by a step-by-step wizard: it recognizes the reference solution on its own, waits for the reading to stabilize, and saves the result with a date.
What it measures
- pH — with temperature compensation
- redox (ORP) — the water's biological condition
- 2× conductivity: a freshwater range (µS/cm) and a marine range (salinity in PSU + specific gravity)
- RO water purity (TDS) in the reserve tank
How it stays accurate
- isolated, shielded measuring circuits — immune to interference from pumps and lamps
- a calibration wizard with automatic reference recognition
- electrode health assessment after every calibration
- calibration reminders every set number of days
Safeguards
- detection of a disconnected or damaged probe — functions that depend on the reading enter a safe state
- an aging electrode → a "time to replace" warning before the reading starts to lie
- raw reading view for service diagnostics
Energy — and diagnostics that get ahead of failures
Each of the power module's eight outlets is metered individually, and the energy meter totals it all: instantaneous power, daily consumption and cost at your electricity rate per kWh. But current metering isn't just statistics — Oquari learns each device's normal power draw and raises an alarm when something deviates from the pattern. A filter drawing noticeably less than usual is air-locked or clogged. A heater that's "heating" without drawing power — just burned out. You hear it from the controller, not from the tank.
What it measures
- each outlet's power draw individually
- a system-wide energy meter (power, kWh, cost)
- circulation and dosing pump power draw
- a UV lamp hour counter
What you get out of it
- daily and monthly charts, the cost of running your tank
- detection of a device that's starting to fail — before it dies
- a UV bulb replacement reminder after its rated hours
Sample diagnostic alarms
- "the filter is drawing 40% less than usual — check for an air lock"
- "the heater is on but drawing no power — probably burned out"
- "pump draw is up by half — possible jammed impeller"
Flood protection and the alarm system
Leak sensors under the tank, in the cabinet and by the reserve tank detect water where it shouldn't be. The reaction is instant and local: stop top-off, dosing and water changes, close the solenoid valves, raise the alarm. Events come in three levels — info, warning, critical alarm — and each level has its own channels: from a quiet log entry to a siren and a push notification. The last 1000 events are always at hand.
What keeps watch
- leak sensors (under the tank, in the cabinet, by the reserve tank)
- minimum and maximum level sensors
- every process raises its own alarms (heating, ATO, dosing, pumps, probes)
How it alerts
- a buzzer and status LED on the device
- an output for an external alarm siren
- push and e-mail notifications (via the oquari.com panel)
- alarm entities in Home Assistant — for your own automations
The overriding rules
- critical alarms work fully locally — no internet, no app
- night quiet hours never cover critical alarms
- an alarm requires your acknowledgment — nothing "just disappears"
- an event log with export — the full history of what happened
Failure resilience — what happens when something goes down
You don't judge a controller by how it works when everything's fine — you judge it by what it does when something stops working. Oquari detects a power outage in a split second: enough time to safely stop top-off and dosing and log the event. When power returns, the system comes back up in a safe order and resumes the program — schedules run on a built-in battery-backed clock, so an 8:00 sunrise happens at 8:00, even if the internet has been out for a week.
The internet goes down
Nothing happens. All logic, schedules and safeguards run locally. You lose only remote viewing — until the connection returns.
The power goes out
The outage is detected immediately, water processes safely stopped, the event logged. On recovery: startup in a safe order, dosing without "catching up" beyond the daily limits.
Modules lose contact
Every module has its own safety reflexes: within seconds the power module keeps filtration and aeration on and switches off the heaters and the rest — on its own, with no hub involved.
A sensor fails
Any function that depends on the reading enters a safe state: heating stops, the CO₂ valve closes, top-off waits. The tank is never run "blind".
This is what peace of mind about your tank looks like
One system in which every function knows about the others — and every one has its own safeguards.