Installing new spa pack. Pack is capable of running 2- 2 speed motors, but I have 2 single speed motors. Does it matter which speed I hook up to (low/high)?

You will want the circulation motor to run when the pack is calling for either high, or low speed. The booster run in high. You can call me.

My systems has a 24hr circulation Grundfus for ozone and heating. I have 2 other single speed pumps and a blower. I just purchased the Balboa 2000le, which can run all these. Just wasn't sure how the high/low circuits worked. I looked at the schematic and there are 2 relays for each pump, 1 for high and 1 for low. Should be just a matter of using the red wire to run them on high speed when needed and 1 of the controller switch positions will do nothing.

I was just going to suggest making a jumper between so the motor will run when either the call for low or high occurs.