Sensors · Water Quality Sondes
Spectra Scientific Spectra Litmus
Water Quality Sondes
Spectra Scientific (spectrascientific.com) Spectra Litmus configurable multiparameter water-quality sonde (Litmus 6 and Litmus 4), read over Modbus RS-485. A central wiper plus interchangeable titanium smart-sensor ports measure water pressure/level and temperature, conductivity, specific conductance, salinity, TDS, density and resistivity, pH/ORP, turbidity/TSS, optical dissolved oxygen, chlorophyll, blue-green algae, and fDOM, plus a broad ion-selective-electrode panel (chloride, ammonium, ammonia, nitrate, and metal/halide ISEs) and barometric pressure. Now withdrawn from the vendor's catalog in favor of resold YSI EXO sondes.
Measures
What the Spectra Scientific Spectra Litmus Measures
23 parameters, each linked to its page: the sensors, units, and standards behind it.
Connects via Thiamis
Models
Spectra Scientific Spectra Litmus Models
2 models, each with what it measures and the ranges its datasheet gives.
| Model | Description | Measures & specs |
|---|---|---|
Spectra Litmus 6 | Flagship configurable sonde: a central wiper plus five interchangeable titanium smart-sensor ports. Carries the full water-quality suite (temperature, conductivity/specific conductance/salinity/TDS, pH/ORP, turbidity/TSS, optical dissolved oxygen, chlorophyll and blue-green algae, fDOM, and the ion-selective electrodes), read over Modbus RS-485, so the parameter set follows whichever sensors are fitted. Bluetooth or wired handheld; up to ~144 days on four D-cell batteries. Withdrawn from the vendor's current catalog. | |
|
Spectra Litmus 4 | Compact sonde: a central wiper plus a smaller bank of interchangeable titanium smart-sensor ports for the same core water-quality parameters, with fewer sensors deployed at once than the six-position Litmus 6. Same Modbus read-out and Bluetooth/wired handheld options. Withdrawn from the vendor's current catalog. |
Standards
Standards for What It Measures
Standards that set limits on the parameters it reports.
Solutions
Where the Spectra Scientific Spectra Litmus Is Used
Solutions whose recommended configuration uses this instrument or whose standards it is built to, followed by solutions whose core panel it partly measures.
Water Quality Monitoring
Rivers, lakes, drinking water, and stormwater
Aquaculture & Fish Farming
Dissolved oxygen, temperature, and ammonia control
Hydrology, Level & Flow
Flood warning, stream gauging, and groundwater
On the platform
What the Spectra Scientific Spectra Litmus Gets From Aethair
Connected through Thiamis, its readings arrive in the same Environet account as Aethair's own monitors.
Live data and alerts
Environet shows the instrument live and alerts the people you choose by email, SMS, and webhook, at the thresholds you set. Noesis sets up a dashboard, a report, or an alert from a plain-text request.
Compliance reports
Aethair Reports produces scheduled or on-demand reports from the instrument's readings, as a PDF or secure link. Templates cover Aethair Blue, WELL v2, cabin air (ISO 23875), and the CMS-2567 healthcare codebook (ASHRAE 170), or you can report against custom limits such as OSHA PELs, NAAQS, EPA guidance, or your own program limits.
Dashboards and the app
Environet dashboards and the Aethair App show the instrument's readings just like any Aethair device. The occupant-facing Aethair Dashboards status display is built around Aethair IAQ and Aethair PRO.
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Questions
Spectra Scientific Spectra Litmus FAQ
What is the Spectra Litmus and how does the integration read it?
The Spectra Litmus is Spectra Scientific's configurable multiparameter sonde: a central wiper plus interchangeable titanium smart-sensor ports (five on the Litmus 6, fewer on the Litmus 4). The Thiamis driver reads it over Modbus RS-485 (9600 8-N-1), polling the full register map every interval. Because it is a configurable smart-sensor sonde, the parameters that actually return values depend on which sensors are fitted to that particular unit.
Is the pressure reading water pressure or barometric pressure?
Both are reported, as separate parameters. Water Pressure (kPa) is the submerged pressure/depth sensor, from which Water Level (m) is also derived; Barometric Pressure (kPa) comes from the sonde's own barometer and compensates the vented level. A third internal 'zero atmospheres' reference is a calibration value rather than a measured parameter, so it is not ingested.
Which parameters does the single Ion-Selective (Other Ions) entry cover?
Chloride, ammonium, ammonia, and nitrate each have their own parameter. The remaining ion-selective electrodes the driver can read (silver, sulfide, fluoride, bromide, iodide, cadmium, lead, potassium, copper (cupric), calcium, cyanide, total nitrogen, and oil-in-water) are folded into the single Ion-Selective (Other Ions) parameter, since a Litmus is rarely fitted with more than one or two of them at a time.
Why do pH, dissolved oxygen, and the algae parameters show two units each?
pH is reported both as pH units and as the raw electrode signal in millivolts. Dissolved oxygen is reported both as concentration (mg/L) and as saturation (%). Chlorophyll and blue-green algae are each reported both as a concentration (µg/L) and as a cell count (pcs/L).
What are the Density and Resistivity readings?
They are conductivity-derived water properties the sonde computes: water density (g/L) and specific resistance / resistivity (MΩ·cm, the reciprocal of conductivity). Both are standard outputs of research-grade sondes (the In-Situ Aqua TROLL and YSI EXO report the same quantities) and are ingested here as their own parameters.
Is the Spectra Litmus still sold?
No. Spectra Scientific has withdrawn its own-brand Litmus 6 and Litmus 4 sondes from its current catalog and now resells YSI EXO sondes for multiparameter monitoring. The Thiamis integration is retained for existing Litmus deployments; 'integrated' here refers to integration status, not product availability.
Sources: spectrascientific.com
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