First let me explain a bit about X-10.
The Aquacontroller sends X-10 signals that include an address which tells which device should respond and a signal that indicates On or Off. The signal is transmitted via the telephone wire with the jack that is connected to the controller. The other end of the wire is connected to the PL513 which in turn is connected to a power outlet. This way the signal from the controller is transmited troughout your house wiring via the PL513.
If you plug an X-10 appliance module to any of your house outlets with the proper address and it will respond on or off depending on the order transmitted.
Now the programming:
X-10 addresses are composed of a leter (A to P) and a number (1 to 16) in theory you can set up to 256 addresses (16 letters times 16 numbers)
The address associated with a device shall match the address in the X-10 module and the device should be connected to the X-10 module of that particular address.
Follow the instructions of the controller manual to name the devices, assign an address and program the functions you want.
As the program gets executed the signal is transmitted to the module via the PL513 to your power lines and the module will respond by turning the device On or Off regarless of where in the power lines is the module/device connected.
As an example if the name you assign to your return pump is PM1 you can assign the name to an address:
PM1#-C16 Here the pump name is associated with the address C16
In the program, lets say you want to turn your return pump in the basement off while feeding:
If Time > 00:00 Then PM1 ON
If FeedA 000 Then PM1 OFF
In this case the first statement tells the controller that the normal state of the pump is ON
The second statement tells the controller that if you activate the Feed timer A the pump shall turn off and stay off as per the setting you entered for the timer FeedA.
When you activate the FeedA timer the controller will sent an OFF signal to the address C16.
For the pump to recieve the signal it is connected to an appliance module for which you set the address C-16 using the dials on the face of the module and connect the module to the nearest outlet in the basement.
So it is really that easy installation and programming wise.
Now for the issues:
The X-10 signal as it travels to the power lines, may encounter different difficulties:
a) Continuity: Many specially larger homes have two different independent 110V circuits comming into the house, this allow for certain devices to operate in 220V like clothes dryers, aircons and electrical range stoves. The issue here is that if the signal is sent in one circuit and the pump is connected to the other circuit the signal may not make it all the way to the pump as it has to travel all the way to the main, from the main to the power company transformer, back trough the other circuit into the house and to the pump. This long travel makes improbable that the signal will reach the module with enough strenght to activate the module.
To solve this problem if you have two circuits in the house, you will need to add what is call an X-10 signal bridge that "Short cuts" both circuits so the signal can travel from one to the other without having to go all the way to teh transformer.
b) Noise: There are many devices that introduce a lot of electrical noise into the power lines, this noise interferes with the X-10 signals so the module can not distinguish a signal from a noise.
This is one of the most difficults problems to solve with X-10. You need to find the source of the noise and isolate the noisy device from the powerlines by using one of many different electronic noise filters. Typical noisy devices are: Ballasts, vacuum cleaners, fluorecent lights and many devices that use electronic switching circuits. In our case the worst ofenders are PC abd T5 ballasts and HQI electronic ballasts. In some cases not even an electronic filter could isolate the problen and the ballast has to be replaced for a different model or type.
Advance PC fluorecent ballasts can be isolated with filters, I found that MH Icecap ballasts of the older type are very quiet and do not require any kind of filter but the newer ballasts although more efficient are extremely noisy and imposible to filter out.
c) Signal atenuation: There are devices that turn into signal sinks that either prevent its transmission like power strips installed with surge protectors or that can absorb the signal like computer power supplies, TVs or Audio systems also installed with surge protection or high frequency atenuators.
Try using cheap power strips which normally do not have surge protection and if need to be you can also use electronic filters to isolate whatever device (Computer, TV etc) causing the issue.
d) Two X-10 signals with the same address: When two signals are transmited wit the same address this will make the module behave very erratical. This could happen two ways. One by mistake assigning the same address to two different devices in the controller and the other when a neighbor is also using X-10 signal and happens to be using one of your selected addresses.
For the first one check and correct your assignments and for the second oone there are two solutions, change your erratic address to a different address or use an isolating device at the main panel, this device will prevent signals from outside from entering the house circuit.
A potential solution to some of the above issues is the use of a signal repeater amplifier. These devices used mainly in big houses were the distances are far from the controller are installed somewhere in the power lines closer to the midle of the travel distance. They will receive the signal, amplify it from the typical 1.5 volts to 5 volts and retransmit it again at a higher strenght.
Because of these potential reliability issues, Neptune when from pure X-10 to the use of Direct Connect modules. If whenever possible use Direct Connect modules if you use both, direct connect and X-10 forst connect the controller to any direct connect and daisy chain them together. The PL513 shall be the last conected in the series and instead to be connected directly to the controller, you connect it to the output outlet of the last direct connect.
Hope this information helps.
There is a lot more information on X-10 in the net, Search for X-10 help, X-10 support and/or X-10 forums.