Chemtrol Pool Controller

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The Chemtrol Pool Controller is a model PC2100 unit (often referred to as the "Chemtrol unit" in the Wiki). It was manufactured by Santa Barbara Control Systems.

In the configuration used at Fairway Farms, it samples ORP (oxidizing properties of a sanitizer, such as chlorine) and pH. It adds calcium hypochlorite (via the "chlorinator") and/or hydrochloric (muriatic) acid (via the "acid pump") to the pool as part of a closed-loop system.

The Chemtrol

Instrumentation

Chemical Probes

The ORP and pH probes are said to be rated for a year of use. In reality, they will probably last longer. Probes should be replaced when readings do not align with those from the chemical test kit (and cannot be corrected for via calibration).

The Chemtrol branded probes are quite expensive. We have had good success with probes (installed in the 2020 season) from Sensorex. The cost is about 75% less than those from Chemtrol.

  • pH5000 Polycarbonate Swimming Pool pH Sensor ($56 as of May 2020)
  • ORP1000 Polycarbonate Laboratory ORP Sensor ($86 as of May 2020)

Flow Meter

The flow meter validates the presence of fresh sampled water as an input to the Chemtrol unit. The flow meter is a Gems RFO-Type 155481, as installed during a service call by Aquatic Source in August 2016.

There is a slight discrepancy to work out with this flow meter - the 1/2" model has a standard flow range of 4 to 20 GPM, per the catalog page. The Chemtrol typically shows about 1 GPM during operation with this sensor.

The wiring for the flow meter is shown in the "PC2100 Auxiliary" (page 43), as part of the Pool Systems Automation Drawings - Auxiliary package.

Procedures

Enabling or Disabling the Chlorinator

The chlorinator is controlled by the Chemtrol unit. The instructions below assume that the Chemtrol unit is operating, and that the main screen is visible.

  1. Press the up or down arrow until the ORP readout is highlighted.
  2. Select the ORP sub-menu by pressing the right arrow.
  3. The first item in the ORP sub-menu selects the feed mode. Press the right arrow to change the mode.
  4. Press the up arrow until the ORP feed mode is AUTO to enable or OFF to disable.
  5. Press the left arrow twice to return to the main screen.

On the main screen, an "A" to right of the ORP reading indicates that the chlorinator is enabled (automatic control), "X" indicates it is disabled.

Enabling or Disabling the Acid Pump

The acid pump is controlled by the Chemtrol unit. The instructions below assume that the Chemtrol unit is operating, and that the main screen is visible.

  1. Press the up or down arrow until the pH readout is highlighted.
  2. Select the pH sub-menu by pressing the right arrow.
  3. The first item in the pH sub-menu selects the feed mode. Press the right arrow to change the mode.
  4. Press the up arrow until the pH feed mode is AUTO to enable or OFF to disable.
  5. Press the left arrow twice to return to the main screen.

On the main screen, an "A" to the right of the pH reading indicates that the acid pump is enabled (automatic control), "X" indicates it is disabled.

Technical Information

  • The left-hand connectors (on the generation of controller that we own) for TDS/Temp, PWFS (paddle wheel flow sensor), Flow and PPM are Conxall/Switchcraft 4-position Mini-Con-X male pin connectors. The mating connectors are Conxall/Switchcraft 6282-4SG-311 and as of January 2021, they are stocked by multiple distributors (Digi-Key, etc).
  • The display is a Newhaven Display NHD-160128WG-BTMI-VZ#-1. If replacing, make note of the required backlight resistor modification. Hawk Electronics of Buffalo Grove, IL stocks this part for $63.30 (as of January 2021). Replacement (at your own risk!) is fairly straightforward for an experienced technician; it requires simply the de-soldering of a header.