Automation, Monitoring and Data

An aquarium controller reads sensors (temperature, pH, salinity, water level, leaks), follows rules someone set, and switches outputs: heaters, pumps, lights, dosing pumps, the top-off. It can log readings, draw graphs and send alerts to a phone.

A controller only knows what its sensors tell it. A probe out of the water, a fouled level sensor or a wrong outlet label all look normal on the screen (Modules 7 and 14). That's why every piece of equipment on every system is still checked and logged every weekday, with the readings compared against separate instruments. IMARCS uses both Hydros and GHL controllers.

Temperature probes read the water around them, so they sit away from heaters and in moving water (Module 14). pH probes need storage, cleaning and calibration (Module 7). Conductivity probes read salinity; some can sit in a separate small vessel for cleaner readings. Level sensors come as floats, optical eyes, capacitive and contact sensors. Leak detectors come as rope sensors laid along the floor or point sensors at one spot. Flow sensors show water moving through a pipe.

Each one reads only its own spot. A level sensor in the wrong chamber, or a temperature probe in still water, gives a true reading of the wrong place. Readings are checked against separate instruments: a second thermometer and a second salinity meter, and a pH probe against a reference solution.

Switched outlets, usually on a power strip, turn heaters, pumps, skimmers and UV on and off. 12 V drive ports run small gear such as an ATO pump, a fan or an RO solenoid valve. 0 to 10 V ports set the speed of variable-speed pumps and the brightness of some lights. Dosing heads pump supplements (Module 19).

Some controllers watch the current each output draws and alert you when a pump stops drawing power or draws too much, which catches a jammed or failed pump. Label every outlet and plug, and make the label match the app; a heater on the outlet the app calls the skimmer is a fault waiting to happen.

Evaporation takes out fresh water and leaves the salt behind (Module 4). An ATO has a level sensor in the pump chamber, the only level that moves (Module 12), and when the level drops it adds fresh water: by a small pump from a reservoir, or by opening a valve on a supply plumbed through a filter. A plumbed supply can refill without limit.

The ATO can't tell evaporation from any other water loss. Water taken out for a task gets replaced with fresh water and salinity drops, so the same amount of matched salt water is added first (Module 4). Top-off water is always fresh, never salt water.

Float switches are cheap and mechanical; they can stick, snails can sit on them, and ripples can make the pump cycle rapidly. Optical sensors have no moving parts and fail less often. Other units use conductivity or heated-tip sensors. Using two different kinds, such as an optical main sensor with a float backup, means one failure is less likely to stop both.

Common failsafes: a backup high-level sensor that stops the pump if the main one fails; a run-time limit that shuts the ATO off if the pump runs too long (10 minutes on the Tunze Osmolator 3155); leak shutoff, as on Red Sea's ReefATO+, which also stops when the reservoir runs dry. Keep the pump's outlet above the reservoir's water so it can't siphon back. A small reservoir limits how much fresh water can ever go in. An outlet timer can cap run time, but not on units that count their own cycles.

Stuck on: fresh water keeps flowing, salinity falls and the sump can overflow. With limewater on the top-off, pH spikes too (Module 19). A plumbed top-off is the biggest risk because it never runs out. Stuck off: evaporation isn't replaced, salinity climbs and the pump chamber runs low until the return pump draws air (Module 12).

Fixes: check the sensor first: free a stuck float, clean a fouled optical sensor, remove snails or crust, and check it's at the right height. Then reset the controller's timeout, refill the reservoir if it ran dry, and watch one full fill. One IMARCS display uses a mechanical float valve on a filtered mains supply, with a backup solenoid valve closed by a float sensor through the controller: two different ways to stop.

Hydros controllers (by CoralVue) link together over a Command Bus cable, which also powers them. Each device has its own processor and schedule and makes its own decisions, so there's no single point of communication failure. Sense ports take temperature probes, optical and capacitive level sensors, leak detectors, flow sensors and switches. Drive ports give switched 12 V for small pumps, fans and RO solenoids, with current monitoring. Probe ports take pH probes.

The Control XS runs WiFi power strips and smart outlets; the X2 adds drive ports; the X4 adds drive ports, probe ports and 0 to 10 V; the X10 adds four dosing heads, salinity, and alkalinity testing with a stirred test vessel, using three of its heads. Everything is set up in the Hydros app, locally over WiFi or remotely through the cloud. The units are splash and dust resistant (IP65).

The ProfiLux 4 (with the 4e, 4.1, 4.1e and the smaller Mini) is a central controller. It has pH and conductivity measurement built in, a water temperature sensor, and inputs for level, flow and leak sensors. It switches up to 64 sockets on PowerBar power strips and drives pumps and lights through 1 to 10 V outputs.

Add-ons include the GHL Doser, the KH Director for continuous alkalinity testing, and the ION Director for calcium and magnesium. It connects by WiFi or USB, has its own web server and email alerts, and uses the myGHL cloud for remote access. The GHL Connect app and GHL Control Center also work entirely on the local network, without the cloud.

Dosing pumps push liquid with rollers squeezing a tube (Module 19). Some use stepper motors, some DC motors. Some stand alone with their own app; others link to a controller. Things to know about each pump on a system: its app, its dose range, how it's calibrated, whether it remembers its settings and clock through a power cut, and whether it delays between heads.

Red Sea ReefDose runs in the ReefBeat app, doses 0.2 to 1,000 mL a day, delays between heads and makes up doses missed in a power cut. Kamoer X1 Pro pumps run from an app, dose 0.1 to 9,999.99 mL at up to 24 times a day, keep their settings through a power cut and can chain up to four pumps. The GHL Doser 2.1 runs alone or with a ProfiLux through GHL Connect and myGHL, and each head is calibrated and primed separately. The Hydros X10 has four heads built in. Every app's container level is a count of what the pump ran, not proof the dose arrived (Module 19).

Set alarm limits outside the range animals live well in. At IMARCS, salinity of 30 to 35 ppt and temperature of 26 to 30 C are livable on every tank, and nothing inside that range should trigger a call. Alarm on what needs action: temperature or salinity outside the livable range, a leak, a top-off timeout or dry reservoir, a pump that stopped drawing current, a controller gone offline.

When an alarm goes off, go and look. Confirm the reading with a separate instrument before acting, since the sensor itself may be wrong (section 11). Alarms that go off for normal conditions teach people to ignore them, so fix the limit or the sensor rather than silencing it.

WiFi or cloud down: Hydros devices make their decisions locally and the GHL apps can work on the local network, so equipment keeps running, but alerts and remote access stop. Sensor wrong: a temperature probe out of the water reads the air, and the controller heats or cools the tank the wrong way while its display looks normal (Module 14). Power cut: know whether each device keeps its schedule and clock and what it does when power returns. Wrong outlet: the app shows an outlet on while the device plugged into it's something else.

Check a controller against separate instruments, never against itself: a second thermometer, a second salinity meter, a pH probe against reference solution. Fix the cause (put the probe back in the water and fix it in place, relabel the outlet, restore the WiFi), then confirm the reading matches.

Controllers graph temperature, pH and salinity, and some log top-off volume and doses. Trends show what single readings can't: slow drift, a heater failing, a top-off suddenly adding twice the water (a leak, a siphon or a heatwave). Red Sea's ReefATO+, for example, logs fills and volume added over 28 days.

Hand logs are kept too (Module 7), one system at a time with its form open. If an instrument reads off, its offset goes on a label on that instrument and is applied by the person recording; log forms never apply offsets automatically. Compare controller graphs with hand-tested readings; when they disagree, find out which is wrong before trusting either.

Every weekday, every piece of equipment on every system is checked and logged, one system at a time with that system's form open, then on to the next. Look at the tank and animals first: the app can't see a pump making noise, salt creep on a power strip or a clam closed up.

Then check the equipment: pumps running, heater and probe placement, top-off reservoir level and sensor, dosing lines and containers (Module 19), outlets matching their labels. Compare controller readings with a second instrument, retest anything that looks wrong before recording it, and log. Anything off gets fixed or reported, with what was already checked.