Spa Controller
The Process Pools AutoPool® and AutoPool®4.0 are both excellent spa controllers.
Although spas are smaller bodies of water they often come with added dangers, added complexity and added challenges. The response to this is that operators often choose (or have mandated) to run at much higher chlorine residuals, which often adds to the difficulty in controlling a spa’s water chemistry rather than alleviating it.
- A spa controller needs to be capable of dealing with the added difficulties associated with spas.
- Temperature – Spas often run at higher temperature, meaning that any spa controller needs to be able to comfortably run at these higher temperatures.
- Volume – Spas are smaller volume meaning, that everything happens more quickly, so any spa controller must be able to react quickly and safely to rapid changes in chemistry. .
- Bubbles – Customers love bubbles, but that degree of agitates can strip chlorine from the water and introduce simple lines, so any spa controller must be able to deal with bubbles.
The AutoPool® and AutoPool®4.0 from Process Pools are spa controllers that are designed to cope with the added complications.
With features such as:
- Temp up to 40°C (104°F).
- Open flow cells (or closed) to deal with bubbles.
- Pool control algorithms run every second.
- Overfeed protection built in.
- Backflush routines built in.
- Boost built in
The spa controllers from Process Pools are arguably the best in the world.
AUTOPOOL® ORP
Includes: Spa controller, pH, temperature, ORP, and 2 control outputs via relays. Back-board mounted with filter and flow regulation and MutoDrive®.
AUTOPOOL® Chlorine
Includes: Spa controller, pH, temperature, free chlorine and 2 control outputs via relays. Back-board mounted with filter and flow regulation and MutoDrive®.
AUTOPOOL® Duo
Includes: Spa controller, pH, temperature, free chlorine, ORP and 2 control outputs via relays. Back-board mounted with filter, flow regulation and MutoDrive®.
FAQ's: Chlorine Disinfection in Public Spas
Chlorine is a powerful and widely used disinfectant that can rapidly kill most bacteria and viruses present in spa water. Maintaining a residual level of chlorine helps continuously inactivate microorganisms and protect bathers. This is generally achieved using an automatic Spa Controller.
Chlorine effectively kills many pathogens quickly (e.g., E. coli in under a minute), but some are much more resistant—Giardia may require ~45 minutes, and Cryptosporidium can take over 10 days at 1 ppm free chlorine and pH 7.5. Maintaining an effective pH and chlorine level is essential in reducing pathogens to an acceptable level, most often achieved using an automated measuring and control system.
- CDC in the USA recommends maintaining a minimum free chlorine level of 3 ppm in public hot tubs. In Europe and other parts of the world free chlorine levels are often much lower at 1-3ppm
- Some local authorities in the USA (e.g., Sonoma County, CA) require 3–10 ppm for spas; if below 3 ppm, they’re closed.
Chlorine (and pH) levels should be tested at least twice daily, and hourly during heavy use periods.
Some UK guidelines recommend measuring free chlorine in hydrotherapy pools at least three times daily.
These guidelines are irrespective of whether or not there is an automatic spa controller installed.
- Free chlorine is the active disinfectant available to kill pathogens.
- Combined chlorine (chloramines) represents chlorine that has already reacted with contaminants and is less effective.
Most authorities recommend keeping combined chlorine below 0.4 ppm to avoid irritation and maintain effectiveness.
- Too low (<3 ppm in parts of the USA): Spa must be closed, and chlorine levels corrected.
- Too high (>maximum safe limit): Typically, above 12 ppm chlorine can irritate bathers; spa must be closed until levels drop. Additionally, proper handling includes never adding chemicals while bathers are in the water and waiting at least 30 minutes after chemical addition before use (unless the chemicals are added slowly and automatically by a spa controller).
Maintain pH between 7.0 and 7.8 (ideally around 7.2–7.6). Chlorine is most effective within this range; lower pH increases corrosiveness; higher pH reduces disinfection efficacy. An automatic spa controller maintains the pH automatically by adding small amounts of acid or alkali to maintain a setpoint
Warmer spa water accelerates chlorine decay. Some guidelines recommend free chlorine of at least 2 mg/L at temperatures above 26 °C. Additionally, maintaining sensor-controlled systems helps manage these fluctuations.
Breakpoint chlorination is the process of adding sufficient chlorine to oxidize chloramines (combined chlorine), restoring effective free chlorine levels. While not explicitly defined in these sources, CDC recommends regular shock treatments (often daily to weekly) to maintain water quality. The use of an automatic spa controller can reduce the need for shock treatments (raising the chlorine level in order to oxidise the chloramines and therefore reduce them).
Yes. Chlorine reacts with organic matter—like sweat, urine, and lotions—to form chloramines (combined chlorine), which are less effective and can cause irritation. This is why maintaining low combined chlorine is important. Also, stabilising agents like cyanuric acid can interfere and are not recommended in hot tubs.
