Apex Classic Firmware version 4.52 is now available as a full public release. This firmware is for use with Apex Classic/Gold, Apex Lite, and Apex Jr. This is not for use with the Apex 2016 model.

As is always a good practice, be sure to utilize the Load/Save feature in the Classic Dashboard to make a backup of your Apex configuration before installing any new firmware. And, do not attempt to update firmware over Wi-Fi.

In this release, the primary fixes and enhancements are:

  • Adds support for the Automatic Top-off Kit (ATK) in the Apex and Fluid Monitoring Module (FMM); this Apex firmware contains new FMM module firmware
  • Fixes a uncommon issue with Radions when a larger quantity of Radion G4s are attached to a WXM; this Apex firmware contains new WXM module firmware
  • Fixes two issues with FMM; this Apex firmware contains new FMM module firmware
    1. FMM inputs sometimes may not appear on the Classic Dashboard if the Apex is an Apex Jr
    2. If an optical sensor is inadvertently connected to a FMM port manually configured for a leak detection sensor, loss of FMM functionality may occur
  • Fixes an issue with DO probe values displaying in PPM even if Saturation range is selected
  • Changes the syntax of the If Error command, and expands its use; previously, If Error was used only with WAVs; it may now be used in any output.
  • Adds a new programming command, 'when'.


See this sticky post for full details about the revised If Error statement and the new When statement.

This release has many other changes which will not be readily apparent to you as end users. Mostly, such changes are code optimizations and fixes for less-common bugs. However, there is one important caveat: v4.5x firmware does not support the PX1000 module, which is an old pre-Apex module that has not been sold for many years. Other legacy/pre-Apex modules such as DC8, DC4, DC4HD, & LunarSim continue to be supported in v4.5x firmware.

Apex Classic firmware 4.5x also changes the If Outlet keyword. The Outlet programming keyword (as in If Outlet ReturnPump = OFF Then OFF) is now simply an alias for a new keyword, If Output. Instead of Outlet, use Output (as in If Output ReturnPump = OFF Then OFF). After upgrading an Apex Classic from an earlier firmware release to 4.5x, all existing programming containing If Outlet statements will automatically be converted to use If Output. You may continue to use If Outlet…., but try to get in the habit of using the new If Output syntax. This change was originally introduced in Apex Classic firmware 4.51, but this change continues to be noted here for the benefit of Apex users who may still be running 4.40 or older firmware on their Apex.

Example: If you enter this programming:


It will be automatically converted to:




The firmware updater for Windows and Mac may be downloaded from firmware download web page. Be sure to follow the instructions on that page after downloading the firmware updater. When updating the Apex, click Update Firmware FIRST; after the firmware has been transferred to the Apex, wait 45-60 seconds for the Apex to reboot, plus an additional minute, then click Update Web Pages. After the web page update is completed, access the Classic Dashboard, then go to Configuration->Module Setup. Update the module firmware for each and every module which shows as "OLD" in the table at the bottom of the Module Setup page. Updating your module firmware if needed is IMPORTANT; do not overlook this last step. An example of an Apex which has three modules with OLD firmware is shown here:



Mac users: The Apex app included in the firmware package for Mac is compatible with OS X 10.10 though 10.12 (Yosemite, El Capitan, and Sierra). To ensure that you use the new Apex app in this package, please choose the Replace option if prompted (as seen in the image below) while installing the new Apex app. Also, if you still have an old version of the firmware updater app named "ApexFlash" installed, you should delete it.