Fallback is a special programming command which, if used in an output's program, tells an output in an AquaBus module what to do if that module loses communications with the Apex base unit or the Apex Jr. Fallback has no effect during normal operations, and cannot be used in lieu of a Set statement. Two examples of when Fallback might "kick in":

  • If the AquaBus cable between an AquaBus module and the rest of the Apex system gets disconnected
  • If the controller fails

Unfortunately, some people on social media tell others that Fallback mode is triggered when the Apex cannot communicate with Apex Fusion due to a loss of network or Internet connectivity. This is absolutely untrue. If the Internet connection at the location of the Apex goes down, or the Apex for some other reason cannot communicate with Apex Fusion, the Apex continues functioning normally, and all output programming continues being executed.

The Fallback command requires one of four parameters: ON, OFF, a % value, or a profile name. The Fallback profilename syntax is only supported by the WAV, and the WXM for Vortech and Radion outputs. Fallback % is supported only for COR, WAV, Vortech, and Lunar outputs. If Fallback profilename is (incorrectly) used for EnergyBar outlets or VDM outputs, it functions the same as Fallback OFF. If Fallback % is (incorrectly) used for EnergyBar outlets or other output types which do not support the use of %, it functions the same as Fallback OFF.

It does not matter where in an outlet program the Fallback statement is used, but the usual convention is to make it the first statement in a program listing. If two Fallback statements are inadvertently used in an outlet program, the last one will prevail. If you use a Fallback statement in a outlet where Fallback is unavailable, that statement will simply be ignored; you should not use a Fallback statement at all in such cases.

This table lists the availability of Fallback for each AquaBus module:

EB4/6/8/832/632 Fallback is supported (ON/OFF) for all AC outlets as well as for the DC24 outputs on EB832 and EB632
ApexJr (A1 aka Classic) - AC outlets Fallback is supported (ON/OFF)
Apex A1, A2, A3 - built-in VarSpd outputs Fallback is not available
Apex A1, A2, A3 - Alarm/warning outputs Fallback is not available
VDM - VarSpd outputs Fallback is supported (ON/OFF only)
VDM - AI serial outputs Fallback is supported (ON/OFF only)
LSM Fallback is supported (ON/OFF/%*)
1LINK - ACC/DC24 outputs Fallback is supported (ON/OFF only); requires 1LINK module firmware 005 or higher
FMM - DC24 output Fallback is supported (ON/OFF only)
AWM Hydra/Vega outputs Fallback is not available. Instead, if the fixture senses a loss of communications, it will slowly dim to a low intensity
WXM - Radion outputs Fallback is supported (ON/OFF/profile)
WXM - Vortech outputs Fallback is supported (ON/OFF/profile/%*)
PM1/PM2/PM3/ASM There are no outlets or outputs, so Fallback is not applicable
ALD There are no outlets or outputs, so Fallback is not applicable
AFS User-defined Fallback is not supported. The AFS always has Fallback OFF
DŌS User-defined Fallback is not available. For safety, DŌS always operates as Fallback OFF, and if a DŌS senses loss of communications, it will shut OFF the pumps if they are running.
WAV - WAV outputs Fallback is supported (ON/OFF/profile/%*)
SKY - SKY outputs Fallback is supported (ON/OFF). Fallback OFF is the default and is strongly recommended.
SKY - Moon outputs Fallback is not available
COR - COR outputs Fallback is supported (ON/OFF/profile/%*)
MXM - outputs for all MXM-attached Mobius lights and pumps Fallback is not handled in the Apex or MXM. Instead, Fallback for all Mobius devices is configured in the Mobius app. If a Fallback statement is present in the Apex programming for any Mobius light or pump, it will have no effect - it will simply be ignored
IoTa/AI lights Fallback ON: The lights will continue to operate using the last spectrum & intensity settings received from the Apex.
Fallback OFF: The lights will turn OFF if they do not receive any communications via the network from the Apex for about 5 minutes.
See the IoTa/AI notes below
Legacy/Virtual Outputs Fallback is not available

*The use of percent (%) values for Fallback of the supported outputs types requires AOS 5.03_AB17 or later for Apex & Apex EL, and AOS 4.53_AB17 or later for Apex Classic models. See this sticky post for more details.

IoTa/AI Lights: Fallback for Apex control of AI Prime/Prime HD/Hydra HD has these requirements and conditions:

  • Your Apex must have AOS 5.05 or later installed
  • Your AI Prime/Prime HD/Hydra HD light(s) must have AI firmware 2.5.x or later installed
  • Your AI lights must all be in normal (Parent) mode; Fallback for light fixtures in Child mode is not supported



The use of Fallback is entirely optional. If you use Fallback, think carefully about the affect on your system if Fallback mode gets activated for any given outlet.