@matt: have you thought about splitting your zones to two groups: the group of valves that are controlled by the float switch would have a common wire that goes through the float switch to the COM terminal. This way, if the switch is off, it cuts the common wire supplied to those valves; the group of valves that are independent of the float switch would have a common wire that goes directly into the COM port. This way, they are not affected by the float switch.
Regarding HTTP station: which firmware version are you using? The latest firmware should have fixed the HTTP station url issue.