Do you need to water cool erhm a water cooled spindle?!!

[HankMcSpank]

Thanks guys... I'm just trying to avoid the extra pipes, buckets, relays & wiring! It sounds like I should be able to get away with it for the type of usage my spindle will see.

[JAZZCNC]

.. I'm just trying to avoid the extra pipes, buckets, relays & wiring!

That said for sake of 2 pipes & bucket it may be worth doing for long runs, better having the option to do it than not.
Regards Relays then Most VFD's have a in-built relay for switching external stuff so just use this. It also saves pump wear has it only comes on when spindles spinning.