Measurements · Water Quality
Chlorophyll
Also known as chlorophyll-a, algae concentration, chlorophyll cell
Chlorophyll-a fluorescence, an indicator of algal biomass.
What it is
What is chlorophyll?
Chlorophyll is the green pigment that algae and aquatic plants use for photosynthesis. Measuring it (usually as chlorophyll-a) gives a direct indication of the amount of algal biomass in the water, reported in micrograms per liter. Because algae are the base of the aquatic food web but also the cause of nuisance and harmful blooms, chlorophyll is a key indicator of a water body's productivity and trophic state: low values indicate clear, nutrient-poor water, while high values indicate a nutrient-rich, algae-laden system. It responds to the nutrients that feed algal growth (nitrate and ammonium), and it is read alongside the blue-green algae channel, which targets the specific pigment of cyanobacteria. Continuous chlorophyll monitoring is the practical way to watch a bloom develop before it becomes a problem.
Because algal blooms drive both water-quality and public-health concerns, chlorophyll is a central parameter in lake, reservoir, and coastal monitoring.
Health and operational effects
A rising chlorophyll signal is the signature of an algal bloom, and blooms bring a cascade of effects. As the algae grow, they can shade out other plants. When the bloom dies and decomposes it consumes oxygen, the classic route to a dissolved-oxygen crash and fish kill. High chlorophyll is one of the defining symptoms of eutrophication, the over-enrichment of water by nutrients, so it is both a warning of nutrient pollution and a predictor of the oxygen and clarity problems that follow. Tracking it gives early warning before those secondary effects arrive.
How it is measured
How Chlorophyll Is Measured
Chlorophyll is measured in-situ by fluorescence. The sensor shines light of a specific wavelength into the water, and chlorophyll in living algae absorbs it and re-emits light at a longer wavelength. The sensor measures that fluorescence, which is proportional to the amount of pigment present. It is one channel of a multiparameter sonde connected to a Thiamis gateway, giving an estimate of chlorophyll and hence algal biomass without taking a sample. As an optical sensor, it is prone to biofouling on its window. A wiper, regular cleaning, and calibration checks keep fouling and drift from distorting the reading over a deployment.
An instrument on Thiamis5
A third-party instrument connected to a Thiamis gateway, reporting into the same Environet account.
Placing chlorophyll sensors
Chlorophyll is measured in-situ by the sonde, and placement matters because algae are not evenly distributed: they concentrate near the surface where there is light, and wind and currents pile blooms against shorelines and intakes. Positioning the sensor at a representative depth, or profiling, captures where the biomass actually is, and siting near a drinking-water intake gives early warning of bloom material arriving. A wiper and routine cleaning keep the optical window clear so the fluorescence signal stays true.
Every device and option that measures Chlorophyll 5
| Device / option | Type | Base platform | Measures |
|---|---|---|---|
 YSI · EXO1, EXO1S, EXO2… | Water Quality Sondes | Thiamis | |
 In-Situ · Level TROLL 300, Level TROLL 400, Level TROLL 500… | Water Quality Sondes | Thiamis | |
 Eureka Water Probes · Manta+ 20, Manta+ 25, Manta+ 30… | Water Quality Sondes | Thiamis | |
 Spectra Scientific · Spectra Litmus 6, Spectra Litmus 4 | Water Quality Sondes | Thiamis | |
 YSI · 6600 V2, 6600EDS V2, 6920 V2… | Water Quality Sondes | Thiamis |
Where it is monitored
Solutions That Monitor Chlorophyll
Each one links to the solution page showing what that industry measures it for.
Aquaculture & Fish Farming
Often addedDissolved oxygen, temperature, and ammonia control
Water Quality Monitoring
Often addedRivers, lakes, drinking water, and stormwater
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Questions
Chlorophyll FAQ
What does chlorophyll tell me about water quality?
Chlorophyll indicates how much algal biomass is present, and therefore how productive or nutrient-enriched a water body is. Low chlorophyll means clear, nutrient-poor water; high chlorophyll means an algae-rich system prone to blooms, oxygen crashes, and eutrophication. It is a direct, early indicator of these problems.
How does a chlorophyll sensor work?
It uses fluorescence: the sensor emits light at a wavelength that chlorophyll absorbs, and measures the light the pigment re-emits at a longer wavelength. The strength of that fluorescence is proportional to the amount of chlorophyll, giving an in-situ estimate of algal biomass without collecting a sample.
How is chlorophyll linked to blue-green algae and dissolved oxygen?
Chlorophyll measures total algal biomass, while the blue-green algae channel targets the specific pigment of cyanobacteria, so the two together show how much of a bloom may be toxic. When any bloom dies and decomposes it consumes oxygen, which is why a chlorophyll rise is often followed by a dissolved-oxygen crash.
How do I monitor chlorophyll?
Deploy a multiparameter sonde with a fluorescence chlorophyll sensor (ideally with a wiper) connected to a Thiamis gateway, logging continuously to catch a developing bloom. Use the configurator to pair a logger with a sonde covering chlorophyll alongside blue-green algae, dissolved oxygen, turbidity, and the nutrient channels.
Monitor Chlorophyll on the Record
Schedule a callConfigure Chlorophyll Monitoring All parameters
A 30-minute call: you tell us about your application, then we demo the solution for it.