hey dezracer i use exactly the same set up the pump runs 24/7 the pumpis so small that it isnt worth the hassle with a timer the contactor is for the light it relays plug into your timer when using HID lights to protect it against the inductive load of the control gear, as ordinary household...
this is our 1st time grow using ghs the church in a hydro setup and a 400w hps from start to finish. real slow to start but flowered at 10 inches and booming now
https://www.rollitup.org/grow-journals/340758-1st-time-grow-greenhouse-seeds.html