Checked with my pool installer. He has only done them with new pools. Has anyone on here had them added after the fact and if so post a pic of the piping? Simple to control on / off using a relay in the panel - of course I am out of relays so I will have to get a bigger one and that is an additional expense. But main question now is can they be added after fact without any negative side effects on performance, etc. etc.? Thanks!!!