--- title: "In-Situ Water Quality Sondes | Aethair" description: "In-Situ TROLL water-level loggers and multiparameter sondes in the Aethair sensor catalog: 14 models for level, conductivity, DO, pH, and more, via Thiamis." url: https://aethair.io/sensors/in-situ-water-quality-sondes/ --- Sensors · Water Quality Sondes # In-Situ Water Quality Sondes In-Situ TROLL instruments: submersible (IP68) water-level and multiparameter loggers. Level TROLL loggers measure water pressure, level, and temperature, and the BaroTROLL measures barometric pressure for level compensation. Aqua TROLL CTD loggers add conductivity, and the multiparameter Aqua TROLL sondes add dissolved oxygen, pH/ORP, turbidity, nutrient ISEs, and algal fluorescence. RDO probes are optical dissolved-oxygen sensors. [Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Build a Configuration](https://aethair.io/build/?params=water_temperature,water_pressure,water_level,pressure,conductivity,specific_conductance,salinity,tds) At a glance **22** parameters **14** models [**Connects via Thiamis** RS-232 · Modbus RTU · RS-485 · Modbus RTU · USB · Modbus RTU](https://aethair.io/products/thiamis/) 2 standards limit what it measures - [EPA drinking water EPA National Drinking Water Standards](https://aethair.io/standards/epa_ndwr/) - [EPA aquatic life EPA Ambient Water Quality Criteria (Aquatic Life)](https://aethair.io/standards/epa_aquatic_life/) Measures ## What In-Situ Water Quality Sondes Measure 22 parameters, each linked to its page: the sensors, units, and standards behind it. [Water Temperature °C / °F / K](https://aethair.io/parameters/water_temperature/) [Water Pressure psi / Pa / kPa / bar / mbar / mmHg / inHg / cmH₂O / inH₂O / Torr](https://aethair.io/parameters/water_pressure/) [Water Level / Depth mm / cm / m / km / in / ft](https://aethair.io/parameters/water_level/) [Barometric Pressure psi / Pa / kPa / bar / mbar / mmHg / inHg / cmH₂O / inH₂O / Torr](https://aethair.io/parameters/pressure/) [Conductivity µS/cm / mS/cm](https://aethair.io/parameters/conductivity/) [Specific Conductance µS/cm / mS/cm](https://aethair.io/parameters/specific_conductance/) [Salinity PSU](https://aethair.io/parameters/salinity/) [TDS ppm / ppt](https://aethair.io/parameters/tds/) [Resistivity Ω·cm](https://aethair.io/parameters/resistivity/) [Density g/cm³](https://aethair.io/parameters/density/) [pH pH / mV](https://aethair.io/parameters/ph/) [ORP mV](https://aethair.io/parameters/orp/) [Dissolved Oxygen mg/L / µg/L / %Sat / Torr](https://aethair.io/parameters/do/) [Turbidity NTU](https://aethair.io/parameters/turbidity/) [TSS ppt / mg/L](https://aethair.io/parameters/tss/) [Nitrate (NO₃) mg/L / mV](https://aethair.io/parameters/nitrate/) [Ammonium (NH₄) mg/L / mV](https://aethair.io/parameters/ammonium/) [Dissolved Ammonia (NH₃) mg/L](https://aethair.io/parameters/ammonia/) [Chloride mg/L / mV](https://aethair.io/parameters/chloride/) [Ion-Selective (Other Ions) µg/L / RFU](https://aethair.io/parameters/ion/) [Chlorophyll µg/L / RFU](https://aethair.io/parameters/chlorophyll/) [Blue-Green Algae µg/L / RFU](https://aethair.io/parameters/bga/) [Connects via **Thiamis**](https://aethair.io/products/thiamis/) Wired interfaces [RS-232 Modbus RTU](https://aethair.io/products/thiamis/#port-rs232) [RS-485 Modbus RTU multi-drop](https://aethair.io/products/thiamis/#port-rs485 "Addressable multi-drop bus: several units share one connector") [USB Modbus RTU](https://aethair.io/products/thiamis/#port-usb) Models ## In-Situ Water Quality Sondes Models 14 models, each with what it measures and the ranges its datasheet gives. | Model | Description | Measures & specs | | - | - | - | | **Level TROLL 300** | Basic vented or non-vented level logger: water level, water pressure, and temperature; entry tier of the Level TROLL line. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Water Pressure](https://aethair.io/parameters/water_pressure/) [Water Level / Depth](https://aethair.io/parameters/water_level/) | | **Level TROLL 400** | Vented or non-vented pressure/level logger measuring water level, water pressure, and temperature. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Water Pressure](https://aethair.io/parameters/water_pressure/) [Water Level / Depth](https://aethair.io/parameters/water_level/) | | **Level TROLL 500** | Titanium vented/non-vented level logger for water level, water pressure, and temperature, with higher accuracy than the 300/400. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Water Pressure](https://aethair.io/parameters/water_pressure/) [Water Level / Depth](https://aethair.io/parameters/water_level/) | | **Level TROLL 700** | Premium level logger with event and linear-average logging and larger memory; measures water level, water pressure, and temperature. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Water Pressure](https://aethair.io/parameters/water_pressure/) [Water Level / Depth](https://aethair.io/parameters/water_level/) | | **BaroTROLL 500** | Barometric pressure and temperature logger used to compensate non-vented Level/Aqua TROLL level data. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Barometric Pressure](https://aethair.io/parameters/pressure/) | | **BaroTROLL** | Rugged barometric reference logger (barometric pressure and temperature) for level compensation. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Barometric Pressure](https://aethair.io/parameters/pressure/) | | **Aqua TROLL 100** | Compact CTD logger: conductivity and temperature with derived specific conductance, salinity, and TDS; no level/pressure sensor. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Conductivity](https://aethair.io/parameters/conductivity/) [Specific Conductance](https://aethair.io/parameters/specific_conductance/) [Salinity](https://aethair.io/parameters/salinity/) [TDS](https://aethair.io/parameters/tds/) [Resistivity](https://aethair.io/parameters/resistivity/) [Density](https://aethair.io/parameters/density/) | | **Aqua TROLL 200** | CTD logger with a pressure/level sensor: water level, water pressure, conductivity, and temperature plus derived specific conductance, salinity, and TDS. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Water Pressure](https://aethair.io/parameters/water_pressure/) [Water Level / Depth](https://aethair.io/parameters/water_level/) [Conductivity](https://aethair.io/parameters/conductivity/) [Specific Conductance](https://aethair.io/parameters/specific_conductance/) [Salinity](https://aethair.io/parameters/salinity/) [TDS](https://aethair.io/parameters/tds/) [Resistivity](https://aethair.io/parameters/resistivity/) [Density](https://aethair.io/parameters/density/) | | **Aqua TROLL 400** | Multiparameter probe: conductivity (specific conductance, salinity, TDS), optical dissolved oxygen (RDO), pH/ORP, temperature, and water level/pressure. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Water Pressure](https://aethair.io/parameters/water_pressure/) [Water Level / Depth](https://aethair.io/parameters/water_level/) [Conductivity](https://aethair.io/parameters/conductivity/) [Specific Conductance](https://aethair.io/parameters/specific_conductance/) [Salinity](https://aethair.io/parameters/salinity/) [TDS](https://aethair.io/parameters/tds/) [Resistivity](https://aethair.io/parameters/resistivity/) [Density](https://aethair.io/parameters/density/) [Dissolved Oxygen](https://aethair.io/parameters/do/) [pH](https://aethair.io/parameters/ph/) [ORP](https://aethair.io/parameters/orp/) | | **Aqua TROLL 500** | Five-port multiparameter sonde with interchangeable smart sensors: RDO dissolved oxygen, pH/ORP, turbidity, and conductivity plus temperature and water level/pressure. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Water Pressure](https://aethair.io/parameters/water_pressure/) [Water Level / Depth](https://aethair.io/parameters/water_level/) [Conductivity](https://aethair.io/parameters/conductivity/) [Specific Conductance](https://aethair.io/parameters/specific_conductance/) [Salinity](https://aethair.io/parameters/salinity/) [TDS](https://aethair.io/parameters/tds/) [Resistivity](https://aethair.io/parameters/resistivity/) [Density](https://aethair.io/parameters/density/) [Dissolved Oxygen](https://aethair.io/parameters/do/) [pH](https://aethair.io/parameters/ph/) [ORP](https://aethair.io/parameters/orp/) [Turbidity](https://aethair.io/parameters/turbidity/) [TSS](https://aethair.io/parameters/tss/) | | **Aqua TROLL 600** | Flagship five-port multiparameter sonde with antifouling wiper. It carries the full Aqua TROLL sensor range (RDO, pH/ORP, turbidity, conductivity, chlorophyll a, blue-green algae (PC/PE), Rhodamine WT, and ammonium/nitrate/chloride ISEs) with derived total and un-ionized ammonia. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Water Pressure](https://aethair.io/parameters/water_pressure/) [Water Level / Depth](https://aethair.io/parameters/water_level/) [Conductivity](https://aethair.io/parameters/conductivity/) [Specific Conductance](https://aethair.io/parameters/specific_conductance/) [Salinity](https://aethair.io/parameters/salinity/) [TDS](https://aethair.io/parameters/tds/) [Resistivity](https://aethair.io/parameters/resistivity/) [Density](https://aethair.io/parameters/density/) [Dissolved Oxygen](https://aethair.io/parameters/do/) [pH](https://aethair.io/parameters/ph/) [ORP](https://aethair.io/parameters/orp/) [Turbidity](https://aethair.io/parameters/turbidity/) [TSS](https://aethair.io/parameters/tss/) [Nitrate (NO₃)](https://aethair.io/parameters/nitrate/) [Ammonium (NH₄)](https://aethair.io/parameters/ammonium/) [Dissolved Ammonia (NH₃)](https://aethair.io/parameters/ammonia/) [Chloride](https://aethair.io/parameters/chloride/) [Ion-Selective (Other Ions)](https://aethair.io/parameters/ion/) [Chlorophyll](https://aethair.io/parameters/chlorophyll/) [Blue-Green Algae](https://aethair.io/parameters/bga/) | | **RDO PRO** | Optical (RDO) dissolved-oxygen and temperature probe; superseded by the RDO PRO-X. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Dissolved Oxygen](https://aethair.io/parameters/do/) | | **RDO PRO-X** | Industrial optical dissolved-oxygen and temperature probe (4-20 mA / Modbus / SDI-12). | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Dissolved Oxygen](https://aethair.io/parameters/do/) | | **RDO TITAN** | Titanium optical dissolved-oxygen probe with active antifouling wiper for long deployments; measures dissolved oxygen and temperature. | [Water Temperature](https://aethair.io/parameters/water_temperature/) [Dissolved Oxygen](https://aethair.io/parameters/do/) | Standards ## Standards for What It Measures Standards that set limits on the parameters it reports. [EPA drinking water EPA National Drinking Water Standards 5 of its parameters](https://aethair.io/standards/epa_ndwr/) [EPA aquatic life EPA Ambient Water Quality Criteria (Aquatic Life) 2 of its parameters](https://aethair.io/standards/epa_aquatic_life/) Solutions ## Where In-Situ Water Quality Sondes Are Used Solutions whose recommended configuration uses this instrument or whose standards it is built to, followed by solutions whose core panel it partly measures. ### [Hydrology, Level & Flow](https://aethair.io/solutions/hydrology/) Flood warning, stream gauging, and groundwater ### [Water Quality Monitoring](https://aethair.io/solutions/water-quality/) Rivers, lakes, drinking water, and stormwater ### [Aquaculture & Fish Farming](https://aethair.io/solutions/aquaculture/) Dissolved oxygen, temperature, and ammonia control On the platform ## What In-Situ Water Quality Sondes Get From Aethair Connected through Thiamis, its readings arrive in the same Environet account as Aethair's own monitors. ### [Live data and alerts](https://aethair.io/platform/environet/) [Environet](https://aethair.io/platform/environet/) shows the instrument live and alerts the people you choose by email, SMS, and webhook, at the thresholds you set. [Noesis](https://aethair.io/platform/noesis/) sets up a dashboard, a report, or an alert from a plain-text request. ### [Compliance reports](https://aethair.io/platform/reports/) [Aethair Reports](https://aethair.io/platform/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](https://aethair.io/platform/dashboards/) Environet dashboards and the [Aethair App](https://aethair.io/platform/app/) show the instrument's readings just like any Aethair device. The occupant-facing [Aethair Dashboards](https://aethair.io/platform/dashboards/) status display is built around Aethair IAQ and Aethair PRO. Similar ## Other Water Quality Sondes ### [Eureka Water Probes](https://aethair.io/sensors/eureka-water-probes-water-quality-sondes/) [Water Quality Sondes](https://aethair.io/sensors/eureka-water-probes-water-quality-sondes/) [Eureka (Solinst) Manta+ multiparameter water-quality sondes: configurable sensor sets for…](https://aethair.io/sensors/eureka-water-probes-water-quality-sondes/) ### [Spectra Scientific](https://aethair.io/sensors/spectra-scientific-water-quality-sondes/) [Water Quality Sondes](https://aethair.io/sensors/spectra-scientific-water-quality-sondes/) [Spectra Scientific (spectrascientific.com) Spectra Litmus configurable multiparameter water-quality…](https://aethair.io/sensors/spectra-scientific-water-quality-sondes/) ### [YSI](https://aethair.io/sensors/ysi-water-quality-sondes/) [Water Quality Sondes](https://aethair.io/sensors/ysi-water-quality-sondes/) [YSI multiparameter water-quality sondes (Xylem): the current EXO platform and the legacy 6-series…](https://aethair.io/sensors/ysi-water-quality-sondes/) Questions ## In-Situ Water Quality Sondes FAQ How does the platform talk to In-Situ TROLL instruments? Over Modbus/RS-485 (19200 baud, 8 data bits, even parity). The logger first reads the instrument's model and serial number, then polls its parameter registers each interval. Fixed instruments (Level TROLL, BaroTROLL, Aqua TROLL 100/200, RDO) return a set parameter list; the Aqua TROLL 600 is scanned so that whichever interchangeable smart sensors are installed are discovered and read automatically. What is the difference between water pressure and barometric pressure on these instruments? The Level TROLL and Aqua TROLL sondes measure hydrostatic water pressure (the pressure of the water column above the sensor), from which water level (depth) is derived. The BaroTROLL instead measures barometric (atmospheric) pressure, which is used to compensate the level readings of non-vented (absolute) sensors. What is the difference between vented and non-vented instruments? Vented (gauge) instruments run a tube to the surface so atmospheric pressure is canceled at the sensor and the reading is the water column only. Non-vented (absolute) instruments are sealed and read water plus atmosphere, so they need a BaroTROLL barometric reference to compensate the derived level. Without it, the level drifts with the weather. How are ammonia, ammonium, nitrate, and chloride measured on the Aqua TROLL 600? The Aqua TROLL 600 carries ion-selective electrodes (ISEs) for ammonium, nitrate, and chloride, each of which can report both concentration (mg/L) and raw electrode potential (mV). Un-ionized ammonia and total ammonia are not measured directly. They are derived from the ammonium ISE together with the sonde's pH and temperature. Which Aqua TROLL sensors are not ingested? The Aqua TROLL sondes optionally carry FDOM, Crude Oil, and Fluorescein WT fluorometers, but this integration does not ingest those channels. Of the fluorescent sensors it reads chlorophyll a, blue-green algae (phycocyanin and phycoerythrin), and Rhodamine WT; Rhodamine WT is reported under the Ion-Selective (other) parameter. Is the RDO PRO still current? The RDO PRO optical dissolved-oxygen probe has been superseded by the RDO PRO-X. Both, along with the wiper-equipped RDO TITAN, measure dissolved oxygen (mg/L, % saturation, and oxygen partial pressure) and temperature using In-Situ's EPA-approved optical RDO method, with no membrane or electrolyte. Sources: [in-situ.com](https://in-situ.com/) · [in-situ.com](https://in-situ.com/pub/media/support/documents/Aqua-TROLL-500-600-700-800_Spec-Sheet_ltr_en.pdf) · [in-situ.com](https://in-situ.com/pub/media/support/documents/AquaTROLL100-200_Spec-Sheet.pdf) · [in-situ.com](https://in-situ.com/pub/media/support/documents/LevelTROLL_Spec-Sheet_ltr_en_0723.pdf)