COVID-19 Update
hth logo


Used in conjunction with hth products and Easiflo® feeders, our range of controllers offer the pool manager precise control of chlorine, pH and temperature with additional optional benefits of variable speed drive control, data logging and multi pool control available.

AquaSense Controllers

Cronos, Crius & Cratos
Traditionally pool chemistry has been controlled by the use of ORP (Redox) or Residual Chlorine Sensors. The quality of the sensors has a huge effect on the ability of the controller to maintain a safe and pleasant bathing water. The sensors used in AquaSense controllers are amongst the best available in the world today and are exactly the same sensors that are used to monitor and control drinking water in many municipal drinking water plants worldwide.

  • Improved Safety - better sensors produce better process control which leads to less variation in chlorine residuals even with highly changeable bathing loads.

  • Improved Control - better process control leads to reduced chemical usage, lower costs and an improved bathing experience.

  • Reduced Costs - lower chemical costs, less expensive controllers and hugely reduced electrical usage are just a few of the ways that the AquaSense controller can save you money.


  • High Quality and Multilingual
  • Single Pool Operation
  • Lowest Purchase Cost of the range
  • Up to 3 sensors typically chlorine, pH or Redox, pH

Options include:

Optical isolation for I/O
4-20 mA outputs
Relays ( solid state or mechanical)
Modbus TCP/ASC11/RTU - A conection for a compatible Building Management System
Flow switch
On / Off control
Analogue control
PID control - Advanced chemical control system


  • Controls up to 2 Volumes of water
  • Low cost
  • Colour display and keypad
  • Sophisticated communications and Control
  • Data logging

All the options of the CRONOS - plus:

Remote internet access
Alarm texts
Inverter / VSD control
Integrated flow control and flow regulation


  • High Quality and Multilingual
  • Up to 4 Pools
  • Medium Cost within the range
  • Colour Touchscreen
  • Data logging

plus all CRONOS and CRIUS options

Energy Conservation with Automatic Control

Most pool recirculating pumps are over specified for the duty required and as such there is scope to turn them down and save considerable amounts of money on the electricity usage. Each pool has a minimum turnover set by the manufacturer or consultant at the time of installation.

Whenever you save electricity you are reducing your CO2 emissions and carbon footprint of your pool and spa and for many organisations, reducing CO2 emissions is a significant factor in choosing which equipment to purchase.

Both the CRIUS and CRATOS controllers allow the user to turn down the recirculating pump during periods of non pool use (overnight) to the minimum level.

During the day while the pool is being used the recirculating pump can be set based on chlorine demand which is proportional to bathing load.

This ability to control the recirculating pump based on chlorine demand means that pool operators can save significant sums of money on electricity during the day when energy costs are at the highest.

Chlorine Sensors
hth controllers offer three sensors to measure; free chlorine, total chlorine, or chlorine in the presence of cyanuric acid. All have a long and low maintenance life of approximately 10 years with reduced calibration requirements. They are manufactured to the highest quality and provide accurate measurement of chlorine, responding rapidly to changing demands within the pool. This means that pools and spas can operate at lower chlorine levels, minimising the formation of unpleasant combined chlorines and reducing the chemical usage, thereby lowering costs and reducing emissions, while providing a better bathing experience.