Use the 2” and reducers…
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The time has come to replace my ancient ball valves. Waiting on the truck to deliver the new Pentairs (cheaper than Jandy, and locally parts are more available). The pool was originally done in all 1 1/2" pipe. When I had my new filter installed, they used 2" from the pump to the filter, and a...
www.troublefreepool.com
A flow switch is activated by water velocity and not actual flow.
The flow switch comes with a T that is designed to provide the correct velocity to match the flow.
Use the T that is provided by the manufacturer so that the flow switch is correct.
For example, if the T is 2", the flow is 25 gpm and if you switch to a 1.5" T, the new flow is activated at 14 gpm.