Tank Calibration

Tank Calibration

Telling TankSync™ how big your tank is and where the water sits in it. This is the step that makes the percentage mean something — until you do it, readings are based on defaults that almost certainly don't match your tank.

Takes about five minutes, and you need a measuring tape.

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Open the tank settings

Open the receiver's dashboard at the IP address shown on its display, then select your tank to open its configuration page.

You can do exactly the same thing from the phone app under Edit Tank — same fields, same effect. See App Overview.

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Name and capacity

Tank Name — anything you'll recognise: Fresh Water Tank, Overhead Tank, Sump. If you have more than one tank, name them now; it's much harder to tell them apart later.

Capacity in litres — your tank's total rated capacity. The default is 1,000 L and it's just a placeholder. This is the number printed on the tank or in its spec, and it's what converts a percentage into litres.

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The two distances — the important part

These two measurements are what the whole calculation rests on. Both are measured from the sensor face, which is the underside of the mount you installed in the lid.

Field	What to measure
Distance When Full	Sensor face → the water surface when the tank is full
Distance When Empty	Sensor face → the bottom of the tank

A measuring tape dropped through the lid opening is the easiest way to get both.

        ┌──────────────────┐  ← lid, sensor mounted here
        │        │         │
        │        │  ← Distance When Full
        │  ~~~~~~▼~~~~~~~  │  ← water surface when full
        │                  │
        │        │  ← Distance When Empty (all the way down)
        │        ▼         │
        └──────────────────┘  ← tank bottom

Distance When Empty is always the larger number. If you enter them the other way round, the tank will read backwards — full when empty, empty when full.

Why "full" isn't zero: there's always a gap between the lid and the highest water level. That gap is Distance When Full. On most overhead tanks it's 15–25 cm.

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Sleep interval

300 seconds — one update every five minutes — is the recommendation and the default.

You can lower it to 60 seconds for faster updates, but every wake costs battery. On a solar transmitter, a short interval through a cloudy week is how you end up with a flat cell. Power Saving has the runtime estimates for each interval.

Changes here apply from the transmitter's next wake, so a 300 s interval means up to five minutes before a new setting takes effect.

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Advanced settings

Sensor Samples — leave at the default of 9. The transmitter takes this many ultrasonic readings per wake and takes the median, which is what rejects the occasional bad echo off a ripple. Raising it costs a little power for very little gain; lowering it makes readings noisier.

LoRa Transmission Power — start at 15 dBm. If the receiver is far away, or there are several walls and floors between the two, raise it gradually — up to a maximum of 22 dBm, and only if you actually need it.

Higher transmit power costs battery on every single send. Raise it only when the signal strength in the dashboard tells you it's warranted, not preemptively.

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Saving

Press Save.

The receiver stores your changes straight away. The transmitter picks them up on its next wake and applies them — you don't need to touch the transmitter, climb to the roof, or re-pair anything.

This means a setting you just saved may take up to one sleep interval (five minutes at the default) to actually take effect on the device. If a change doesn't seem to have applied, wait one cycle before assuming something's wrong.

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Checking your calibration

The quickest sanity check: compare what the dashboard says against what you can see.

• Tank visibly full but reads 60%? Your Distance When Full is too large.
• Tank visibly empty but reads 30%? Your Distance When Empty is too small.
• Percentage moves the wrong way as the tank fills? The two distances are swapped.

The raw sensor distance is shown on the tank card and in the tank detail view — that's the unprocessed measurement, and it's the fastest way to tell whether the sensor is reading correctly but calibrated wrongly, or not reading properly at all.

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Alert thresholds

From the same page you can set the levels that trigger low-water and overflow alerts. Those feed the buzzer on the hub (Local Web UI), push notifications in the app (App Settings), and Home Assistant if you use it (HACS Integration).