Gravity: Analog TDS Sensor/Meter for Arduino measures the value of the water, to reflect the cleanliness of the water. It can be applied to domestic water, hydroponic and other fields of water quality testing.
TDS (Total Dissolved Solids) indicates that how many milligrams of soluble solids dissolved in one liter of water. In general, the higher the TDS value, the more soluble solids dissolved in water, and the less clean the water is. Therefore, the TDS value can be used as one of the references for reflecting the cleanliness of water.
Gravity: Analog TDS Sensor/Meter for Arduino supports 3.3 ~ 5.5V wide voltage input, and 0 ~ 2.3V analog voltage output, which makes it compatible with 5V or 3.3V control system or board. Gravity: Analog TDS Sensor/Meter for Arduino excitation source is AC signal, which can effectively prevent the probe from polarization and prolong the life of the probe, meanwhile, increase the stability of the output signal. The TDS probe is waterproof, it can be immersed in water for long time measurement.
SPECIFICATION
Signal Transmitter Board
- Input Voltage: 3.3 ~ 5.5V
- Output Voltage: 0 ~ 2.3V
- Working Current: 3 ~ 6mA
- TDS Measurement Range: 0 ~ 1000ppm
- TDS Measurement Accuracy: ± 10% F.S. (25 ℃)
- Module Size: 42 * 32mm
- Module Interface: PH2.0-3P
- Electrode Interface: XH2.54-2P
TDS probe
- Number of Needle: 2
- Total Length: 83cm
- Connection Interface: XH2.54-2P
- Color: Black
- Other: Waterproof Probe
Connection Diagram
Turbidity, Total Suspended Solids & Water Clarity
Total suspended solids
Total suspended solids (TSS) are particles that are larger than 2 microns found in the water column. Anything smaller than 2 microns (average filter size) is considered a dissolved solid. Most suspended solids are made up of inorganic materials, though bacteria and algae can also contribute to the total solids concentration .
These solids include anything drifting or floating in the water, from sediment, silt,and sand to plankton and algae . Organic particles from decomposing materials can also contribute to the TSS concentration. As algae, plants and animals decay, the decomposition process allows small organic particles to break away and enter the water column as suspended solids . Even chemical precipitates are considered a form of suspended solids . Total suspended solids are a significant factor in observing water clarity . The more solids present in the water, the less clear the water will be.
Some suspended solids can settle out into sediment at the bottom of a body of water over a period of time . Heavier particles, such as gravel and sand, often settle out when they enter an area of low or no water flow. Although this settling improves water clarity, the increased silt can smother benthic organisms and eggs . The remaining particles that do not settle out are called colloidal or nonsettleable solids .
These suspended solids are either too small or too light to settle to the bottom.
Settleable solids
Settleable solids are also known as bedded sediments, or bedload . These sediments can vary from larger sand and gravel to fine silt and clay, depending on the flow rate of water. Sometimes these sediments can move downstream even without rejoining the suspended solids concentration. When settleable solids are moved along the bottom of a body of water by a strong flow, it is called bedload transport .
Turbidity is an optical determination of water clarity . Turbid water will appear cloudy, murky, or otherwise colored, affecting the physical look of the water. Suspended solids and dissolved colored material reduce water clarity by creating an opaque, hazy or muddy appearance. Turbidity measurements are often used as an indicator of water quality based on clarity and estimated total suspended solids in water.
Turbidity of Water
The turbidity of water is based on the amount of light scattered by particles in the water column . The more particles that are present, the more light that will be scattered. As such, turbidity and total suspended solids are related. However, turbidity is not a direct measurement of the total suspended materials in water. Instead, as a measure of relative clarity, turbidity is often used to indicate changes in the total suspended solids concentration in water without providing an exact measurement of solids .
CDOM
Turbidity can come from suspended sediment such as silt or clay, inorganic materials, or organic matter such as algae, plankton and decaying material. In addition to these suspended solids, turbidity can also include colored dissolved organic matter (CDOM), fluorescent dissolved organic matter (FDOM) and other dyes . CDOM is also known as humic stain. Humic stain refers to the tea color produced from decaying plants and leaves underwater due to the release of tannins and other molecules.
This discoloration is often found in bogs, wetlands or other water bodies with high amounts of decaying vegetation in the water. CDOM can cause water to appear red or brown, depending on the type of plants or leaves present. These dissolved substances may be too small to be counted in a suspended solids concentration, but they are still part of a turbidity measurement as they affect water clarity.
Total suspended solids, as a measurement of mass are reported in milligrams of solids per liter of water (mg/L) . Suspended sediment is also measured in mg/L . The most accurate method of determining TSS is by filtering and weighing a water sample . This is often time consuming and difficult to measure accurately due to the precision required and the potential for error due to the fiber filter .
JTU
Turbidity, on the other hand, is most often measured with a turbidity meter. Turbidity is reported in units called a Nephelometric Turbidity Unit (NTU), or a Jackson Turbidity Unit (JTU) . The JTU was the original turbidity unit based on the visibility of candlelight in a tube (Jackson Candle Turbidimeter) . However, this method is considered out of date and inaccurate in comparison to newer methods.
NTU
While some organizations consider the two units to be approximately equal, there are some specific differences . In particular, NTU is more precise and has a wider range (JTU cannot measure above 25 JTU/NTU) . In addition NTU is the standard unit of many broadband output (400-680 nm wavelength) turbidit meters. Nephelometric refers to the measurement technology used. This technology method requires the photodetector in the meter to be placed at a 90 degree angle from the illumination source . As light bounces off the suspended particles, the photodetector can measure the scattered light.
FNU
The USGS also suggests the use of the Formazin Nephelometric Unit (FNU) if a turbidity meter only has a monochrome/infrared output, as opposed to the white/broadband output . This applies to instruments that are in compliance with the European drinking-water protocol, including most submersible turbidity meters . Both NTU and FNU will show equal measurements when calibrating as they both use nephelometric technology, but may operate differently in the field due to the different light source . Turbidity meters that use FNU units are able to compensate for dissolved colored materials (such as humic stain), while NTU turbidity meters cannot .