Did you install a bridge or a filter? If you installed a bridge, that only allows the signals to reach multiple phases in the home....it doesn't filter your panel from outside signals (other x-10 units in the neighborhood).
You can install a filter at the service panel
like this one that should eliminate the outside interference. I also use x-10 with the aquacontroller, and can tell you that there are a lot of things you can try to help reduce the problem.
First, try a different letter code for the problem units. Keep trying different ones until the problem stops.
Second, you might want to make sure it isn't getting interference from your lights...try and make sure all ballasts are isolated and mounted as far from the x-10 unit as possible.
Third, disable the "auto-on" feature of the modules. To disable the local control feature, read
this.
Fourth, you can try to use single-outlet noise filters found
here. I have found that this sometimes helps.
Finally, you could get the PC module and hook your computer up to the wiring to "listen" for bogus signals. This would tell you if the aquacontroller is malfunctioning. If you detect the signal on the wire, disconnect the aquacontroller and continue to monitor the wire.
They are a little tricky to get going, but once you have found all the "bugs" x-10 can be pretty reliable.......good luck
Dave