Compact DS (CDS)

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If our standard DS5 unit is too big and our standard MS5 unit is too long for your application, consider the "Compact DS". It’s only 21.5”long x 2.6” in diameter x 3.8 lbs and fits in a standard backpack.

It’s also a good replacement for the YSI® 6920V2 ( Which measures 22” long x 2.9” in diameter x 5.5 lbs ) .  

The Compact DS can be fitted with the same cable connector as the 6920V2® and can communicate to a PC or a Datalogger using your existing cables. No need to purchace or reinstall field cables.


Compact DS:

  • Is only 21.5” long and 2.6" in diameter, which makes it very portable.
  • Fully compatible with the Hydrolab SVR4A® hand-held unit. There is no need to buy a new display, if you have one.
  • Supports SDI-12 communication protocol. It will easily connect to a datalogger like Sutron®, Handar®, Waterlog®, or any datalogger that uses SDI-12.
  • Supports RS232 communication protocol. It will easily connect to a PC or PDA.
  • Internal Battery Pack. 8 AA batteries for unattended deployments when needed. 

CDS sensorhead Transp

Measures up to 10 parameters simultaneously:

  • Temperature in °C and °F
  • Conductivity in µS/cm and mS/cm
  • Salinity in ppt 
  • TDS
  • pH 
  • Dissolved Oxygen in mg/l and % 
  • ORP (Redox) in mV
  • Depth in meters or feet
  • Total dissolved gas “TDG” mmHg
  • Self clean Turbidity sensor 

Specs Compact DS:

  • Size: Outer diameter: 2.6” (6.6 cm)
  • Length: 21.5” (54.61 cm)
  • Weight: 3.8 lbs/1.7 kg. ( Fully loaded) 
  • Computer Interface: RS-232, SDI-12 and RS-485
  • Memory: 120,000 measurements
  • Operating Temperature: -5 to 50 °C
  • Maximum Depth: 225 m
  • Internal Battery Pack: 6AA 

The Temperature sensor is a 30k ohm variable resistance thermistor.

CDS Compare CDS to DS

The temperature sensor is included with every Hydrolab sonde.

  • Range: -5 to 50 °C
  • Accuracy: +/- 0.10 °C
  • Resolution: 0.01 °C

The HydroTech Dissolved Oxygen sensor is based on a standard Clark cell design, which is EPA approved, and has been trusted for over 30 years. Solid state silver anode for extended operational life span. Optional Titanium Circulator allows enough flow through the dissolved oxygen membrane even in zero flow condition for more accurate DO measurement. The Titanium Circulator is fully sealed with o-rings and can be serviced if needed. 

  • Range: 0 to 50 mg/l
  • Accuracy: +/- 0.2 mg/L for 20mg/L or less, +/- 0.6 mg/L for over 20 mg/L
  • Resolution: 0.01 mg/l

Optional Optical Dissolved Oxygen  sensor: 

  • Range: 0 to 20 mg/L
  • Accuracy: +/- 0.1 up to 8 mg/L ; +/- 0.2 above 8 mg/L
  • Resolution: 0.01 mg/L

The Conductivity sensor uses four graphite electrodes in an open cell design.

  • Range: 0-100 mS/cm
  • Accuracy: ± (0.5% of reading + 0.001 mS/cm)
  • Resolution: 0.001

The pH sensor uses a glass bulb and refillable reference electrode.

The ORP sensor uses a simple platinum band that donates or accepts electrons

to monitor chemical reactions, quantify ion activity, or determine the oxidizing or reducing properties of a solution.


  • Range: 0 to 14 pH units
  • Accuracy: +/- 0.2 units
  • Resolution: 0.01 units


  • Range: -999 to 999 mV
  • Accuracy: +/- 20 mV
  • Resolution: 1 mV

Custom-made Pressure sensors with two range options.

  • Range: 0 to 25m or 0 to 100m
  • Accuracy: +/- 0.05 meters
  • Resolution: 0.01 meters

The Total Dissolved Gas (TDG) sensor uses a pressure transducer mounted behind a rigid gas-permeable silicone membrane to measure the amount of total gaseous compounds dissolved in a liquid. Maximum water depth is 25 m.

  • Range: 400 – 1300 mmHg
  • Accuracy: +/- 0.1% of span
  • Resolution: 1.0 mmHg

The Self-Cleaning Turbidity sensor measures from 0 to 3000 NTU and includes a user-programmable cleaning system to remove any fouling or debris that could otherwise affect readings.

Range: 0-3000 NTU

  • Accuracy (compared to Stable-Cal): 1% up to 100 NTU, 3% from 100-400 NTU, 5% from 400-3000 NTU
  • Resolution: 0.1 NTU from 0-400 NTU; 1 NTU for >400 NTU
  • Temperature Coefficient: 0.05%/C

Most common questions and answers:

Q: Does the Compact DS use the same communication protocol as the Datasonde®? 

A: Yes. The Compact DS uses the same firmware as the Datasonde® with all its features.

Q: Can I use the Hydras 3 LT to communicate with the Compact DS? 

A: Yes.

Q: Can I use the Hydras 3L Pocket software with the Compact DS? 

A: Yes.

Q: Can I use my existing Hydrolab® cables to connect to the Compact DS? 

A:  Yes. The standard Compact DS comes with the standard Hydrolab® 6 pin cable connector.

Q: I do not like the standard Hydrolab® 6 pin cable connector, can the Compact DS be fitted with a YSI® type connector? 

A: Yes. The "Compact DS" can be fitted with an optional YSI® type cable connector with recessed pins for maximum ruggedness and it will work with your existing YSI® cables.

Q: Does the Compact DS have internal memory? 

A: Yes, it has enough internal memory for 120,000 measurements.

Q: Which batteries does the Compact DS use ? 

A:  The Compact DS is equipped with a 6 AA internal battery pack.  They are designed for short unattended deployments only ( one to four weeks  depending on the setup). 

Q: Does the Compact DS require internal batteries when used with the SVR4A®? 

A:  No, the Compact DS does not require internal batteries when used with the SVR4® display.

Q: Does the Compact DS require internal batteries when used with the NX7-B PDA or the Algiz 10X tablet? 

A: No, the Compact DS does not require internal batteries when used with the NX7-B PDA or the the Algiz 10X tablet.

Q: Does the Compact DS require internal batteries when used with the computer ?

A:  When used with a computer, the Compact DS does require external power or an internal battery pack.

Q: When connected to a Datalogger, can the Compact DS still log data internally ? 

A: Yes. The Compact DS can perform all the following tasks simultaneously: 

    • Communicate with a PC or Handheld unit via RS232 or RS422
    • Communicate to a datalogger via SDI-12 or RS232 
    • Log data to its internal memory up to 4 files at a time, even with overlapping dates

 For a quote please email your request to sales or call 512-846-2893

       © Hydrotech ZS Consulting 2016