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HydroCycle PO4
The HydroCycle-PO4 is a wet chemical sensor engineered for environmental monitoring to enable valid, scientifically defensible results that lead to better management recommendations. A NIST traceable on-board standard, factory calibration check, a 2.3 µgP/L detection limit, and an accurate calibration mean you can trust data, line up grab sample records, and swap sensors with minimal offsets.
Autonomous operations, low-power, five month reagent stabilityenable extended deployments in remote locations. Over 1000 samples between services, up to four samples per hour and both SDI-12 and RS232 permit capturing higher frequency phosphate data than before.
The HydroCycle-PO4 has increased reliability over its predecessor, the Cycle-PO4, and many wet-chemical sensors, by maximizing data reliability and sensor uptime. Fluidics have been advanced to provide > 90% uptime free of bubbles for data quality in high oxygen saturation environments and to ensure it stabilizes rapidly after deployment. Filter life has been extended to minimize clogging and enhance data quality during high sediment events.


  • Robust: Excellent anti-fouling capability provided by copper mesh screens and 10 µm stainless steel intake filters

  • Accurate: Nanomolar resolution and scattering insensitive optical cell

  • Cost Effective: Over 1000 samples including onboard spike calibration for QA/QC, typical deployment duration of three months, reducing field costs


1.1 Mechanical

Rated Depth

200 m

Weight in Air

6.8 kg (with reagents)

Weight in Water

0.37 kg

Height (with handle)

56 cm


18 cm

Temperature Range, Operation

0 - 35 C


1.2 Electrical


Main Port (6-pin)

RS232/SDI-12 Port (8-pin)


10.5 -18 VDC

Current Draw, Operation

115 mA, 3 A max

125 mA avg, 3 A max 

Current Draw, Low Power

0.25 mA

1.0 mA

Power Dissipation

1.15 W avg, 12 W max

Communication Interface



Data memory

1 GB CF Card Type II


1.3 Optical


870 nm


5 cm


> 95% R2


1.4 Analytical

Detection limit, three standard deviations of 18 MOhm water

equal to or less than 0.0023 mg/L PO4-P

Quantification limit, ten standard deviations of 18 MOhm water

 equal to or less than 0.0077 mg/L PO4-P

Standard deviation of standard solution of 2.6 µM

equal to or less than 0.0015 mg/L PO4-P


Range, nominal

 0-0.3 mg/L PO4-P

* A higher range of 0 - 1.2 mg PO4-P is possible but outside of specifications. 

Specifications are subject to change without notice.

Related Categories
Water Quality Multiprobes
Aqualab Systems