For those who are using dual Aquastreams with an Aquaero there is a simple way to mount both Aquastream controllers to the Aquaero. It comes stock with the ability to add one controller to the back. To get both controllers on the back you need to disassemble the main Aquaero board from the display. There are six (6) socket head cap screws that need to be removed. Then you can separate the display from the main board if you have a pin and socket connection on late model Aquaero's. If it is soldered together you will have to figure out how to do this yourself. On the front side of the mainboard there are two socket head cap screws that hold on the hex metal stand-offs. Take this off and replace it with the type that has a female on one end and a male on the other end. I used a 6-32 x 1" stand-off. The female side of the stand-off is screwed to the Aquaero mainboard. You then add an Aquastream controller as usual over the male threads. Then take a double female stand-off of the same thread size you used earlier and screw it on to the other male threaded stand-off. Now you add the second Aquastream controller and tighten it down to the stand-off just like you would normally do if you were using a stock unit.
Now you have an Aquaero with both Aquastream controllers conveniently located so that you can easily use the standard 4 1/2" Aquaero-Aquastream 10 pin cable to connect all three devices by just adding a 10 pin ribbon crimp on connector. ;D
One added bonus by using a 1" male/female stand-off and 3/4" double female stand-off is that it moves the Aquastream contoller far enough away from the Aquaero that you can easily attach the relay connector without having to disassemble your hardware.