Does anyone have any information on using a flow switch to help automate a peristaltic pump on an attached spa/pool? I want the peristaltic pump to operate whenever the the pool is circulating, but I do NOT want it to run when I switch the flow over to the spa. Even if I put the injection point down stream of the return valve (on the pool side of the flow), I won't want the peristaltic constantly injecting chlorine into the pipe when the spa is running. Simply hooking the injector pump to the main pump timer would require me to always remember to separately switch the peristaltic pump off when using the spa, and back on again when I'm finished so that it runs on the next pool pump cycle. Even though I would probably not forget to do this, I don't trust that others will remember, and I'd like to keep things more automated.
My thinking was that I could still put the peristaltic pump on the main timer, but that I could ALSO attach it to a flow switch on the pool side of the return flow. This way, the main pump would have to be on AND the flow would have to be on the pool side for the peristaltic to work.
The problem is that I don't know much about flow switches other than knowing that they are used for things like SWCGs and heaters. I found some on the web, but it would be helpful to get some direct feedback from others who have done this sort of thing.
I'm not sure about some of the specs, and I'm not clear about certain details, like if the flow switch needs to go downstream of the injection point (i.e. if the flow switch would be effected by the higher chlorine levels.) On my system, it would solve some hookup issues if I could put the switch AFTER the injection point, but intuition tells me that this might damage the switch over time.