I recently installed a new Hayward EC75 (40sqft) and a Pentair 1-1/2 HP 2-speed pump. With everything fresh and clean, I see about 10psi on the gauge when the pump is on high. When I switch it to low speed, the gauge goes to about 1psi, but the water is still flowing. Not nearly at the velocity of the high setting, but it's moving. Should I be concerned? Is the low setting usable at this pressure? I've left it on high through the initial spring cleanup, but now that the water is clear, I'm considering switching to low. Will it be effective at this pressure?