I am using the x-10 powerline pro. The controller is a aquanode controller. It is used around alot of electronic ballast and pumps. So there is alot of noise. I have used noise filters on every item. The ballast are 400w each and there is 9 of them. I tried to use the modules on them however they are not reliable since some will not turn on and some that do will turn off on there own and then turn back on. Which is not good for MH bulbs nor the ballast. Can I use something like a RS-485?
If you mean can you convert wireless PLC protocol X10 modules to wired RS-485 protocol...in practical sense, no. You would be trying to re-invent the wheel.
Dan is right, "X10 Powerline Pro" tells us nothing.
What kind of X10 Powerline Pro modules are you using? (I'm going to assume Appliance modules PAM01 or 02 for each light?)
What kind of noise filters are you using? Are they X10? What is the part number?
Metal Halide lights are notoriously noisy.
What is the X10 interface between the Aquanode and the powerline (i.e. PSC04, PSC05, CM11A, CM15A)?
Do you have a X10 repeater to boost the X10 signal? If not, you would probably benefit from one such as the XTB IIR.
When you say your lights turn off and come right back ON, you are probably seeing the X10 modules "local control" circuit turn the light back on when the starter circuit in your MH light resets. Try putting a 7 watt night light on the same module as the troublesome lights. Search this forum for "local control" for information.
or go here:
http://jvde.us/x10_troubleshooting.htm